Written heat illness prevention plan requirements by state

Last updated 2026-07-09

Does federal OSHA require a written heat illness prevention plan?

Not yet, but it's close. Federal OSHA published a proposed heat illness prevention rule on August 30, 2024, in the Federal Register ^[1]. That proposal would require employers in general industry, construction, maritime, and agriculture to develop a written Heat Injury and Illness Prevention Plan (HIIPP) whenever workers are exposed to heat at or above an initial heat trigger of 80°F or a high heat trigger of 90°F. The written plan would need to cover heat monitoring procedures, water and rest access, acclimatization schedules, emergency response steps, and training records.

The rule is still in rulemaking as of mid-2025. Final publication could land in 2025 or 2026, depending on the regulatory calendar and any administration-level review. Until a final rule is published and its effective date passes, federal OSHA enforces heat hazards through the General Duty Clause, Section 5(a)(1) of the OSH Act, which requires employers to protect workers from recognized serious hazards even without a specific standard ^[2]. OSHA has cited employers under the General Duty Clause for heat-related deaths, so "no specific standard" does not mean "no risk."

If you operate in a state-plan state, your state agency may already have its own standard with real written plan requirements right now. Read those sections carefully before you assume the federal gap protects you.

Which states currently require a written heat illness prevention plan?

Five state-plan states have enforceable written heat illness prevention plan requirements: California, Colorado, Minnesota, Oregon, and Washington. Each sets its own triggering temperature, covered worker populations, and content rules. Here is the side-by-side.

State	Standard reference	Heat trigger (outdoor)	Written plan required?	Indoor coverage?
California	8 CCR § 3395	80°F	Yes	Limited (some industries added 2024)
Colorado	7 CCR 1101-5	80°F	Yes	Yes (all industries)
Minnesota	MNOSHA 5205.0110	77°F (WBGT-based)	Yes	Yes
Oregon	OAR 437-002-0156	80°F	Yes	Yes
Washington	WAC 296-62-095	89°F (outdoor and indoor)	Yes	Yes

A few things jump out of that table. Minnesota uses Wet Bulb Globe Temperature instead of dry-bulb air temperature, which changes how you measure the trigger. Washington's 89°F threshold is the highest of the group, but it applies both indoors and outdoors. Colorado's rule covers every industry from day one, more than agriculture or construction.

No other state-plan state (Arizona, Hawaii, Indiana, Iowa, Kentucky, Maryland, Michigan, Nevada, New Mexico, North Carolina, Puerto Rico, South Carolina, Tennessee, Utah, Vermont, Virginia, Wyoming) currently has a promulgated, enforceable written heat plan standard, though several publish guidance documents or have pending rulemaking. Check your state OSHA website directly before you conclude you have no state obligation.

What does California's heat illness prevention plan require?

California's outdoor heat illness prevention standard, 8 CCR § 3395, has been in force since 2005 and is the oldest state heat rule in the country ^[3]. Cal/OSHA enforces it hard, especially in agriculture, construction, landscaping, and oil and gas. The written plan must be in English and the language understood by the majority of workers, kept at the worksite, and made available to employees and Cal/OSHA representatives on request.

At a minimum, California's written plan must address: procedures for drinking water (at least 1 quart per employee per hour), cool-down rest periods in shade (at least 5 minutes of preventive cool-down rest when a worker feels the need), emergency response procedures, observation and monitoring of workers for signs of heat illness, and close observation of new employees during their first 14 days (the acclimatization period).

California added an indoor heat rule in 2024 covering most workplaces where the temperature reaches 82°F ^[4]. That indoor rule, effective July 2024, requires a written Indoor Heat Illness Prevention Plan as a separate document from the outdoor plan. The indoor plan must identify work areas where workers may be exposed, list steps to control heat, name cool-down areas, and set emergency procedures. Employers with both indoor and outdoor exposure need two plans, or one combined plan that clearly covers both environments.

Cal/OSHA citation data shows heat illness among the most frequently cited serious violations in California agriculture and construction. The agency can issue willful citations with penalties up to $156,259 per violation as of 2024 ^[3].

What does Oregon's heat illness prevention standard cover?

Oregon's heat illness prevention rule, OAR 437-002-0156, took effect June 15, 2022, for general industry and agriculture, and applies to both outdoor and indoor work ^[5]. The written plan requirement kicks in at 80°F.

Oregon's written plan must document: the specific location of water and shade or cooling areas, the acclimatization schedule for new workers, procedures for spotting and responding to signs of heat illness, emergency medical response contacts, and communication procedures between supervisors and workers. Oregon OSHA publishes a free template on its website, worth downloading even if you adapt it rather than use it as-is.

One Oregon requirement catches employers off guard. You must designate someone at each worksite who is responsible for monitoring heat conditions and running the plan, and that designation has to be written into the plan itself. If that person changes, the plan needs updating. Small details like that are exactly what Oregon OSHA inspectors check during complaint investigations.

What does Washington's heat rule require for written plans?

Washington's heat illness rule, WAC 296-62-095, has been in effect since May 2008 and was updated in 2023 ^[6]. Washington uses an 89°F threshold, higher than California or Oregon. Don't let that number lull you. Washington also has an acclimatization trigger that applies starting on the first day a new worker is exposed to heat, no matter the temperature.

The written plan requirement applies once temperatures hit 89°F indoors or outdoors. The plan must include procedures for water access (at least 1 quart per person per hour), rest breaks in shade or a cool area, emergency response steps, and a supervisor training record. Washington L&I publishes a model program you can start from.

Washington's rule stands out for one thing. It specifically requires employers to monitor weather forecasts and adjust work schedules ahead of time when a heat advisory is in effect. That forecast-monitoring duty has to be documented in the written plan, which surprises employers who assume the plan sits static in a binder.

What does Colorado's heat illness prevention rule require?

Colorado adopted its heat illness prevention rule effective May 1, 2023, one of the newest state standards ^[7]. Colorado OSHA's rule applies to all industries, more than outdoor work, whenever indoor or outdoor temperatures reach 80°F.

Colorado's written plan must include: a heat monitoring protocol (who measures temperature, how often, with what equipment), water and rest procedures (1 quart per hour minimum, shaded rest areas reachable within 2 minutes), an acclimatization schedule for workers new to heat exposure or returning after 5 or more days away, a process for workers to report symptoms, and emergency response procedures with contact information for emergency services. Employers also have to record and retain their heat monitoring measurements.

Colorado's rule stands out because it plainly covers indoor workers in warehouses, kitchens, laundries, and manufacturing plants. Plenty of employers in those industries assumed they sat outside the scope of heat rules. In Colorado they don't.

What does Minnesota's heat standard require?

Minnesota's heat standard, MNOSHA 5205.0110, uses Wet Bulb Globe Temperature (WBGT) as the trigger metric instead of plain air temperature ^[8]. WBGT accounts for humidity, radiant heat, and air movement, so it measures actual heat stress more accurately. The thresholds vary by workload level (light, moderate, heavy, very heavy), with the lowest action level starting at a WBGT of about 77°F for heavy work.

The written plan obligation requires employers to identify heat sources in the workplace, assess exposure levels by job task, document control measures, train workers on recognition and response, and keep records of heat illness incidents. Minnesota's approach reads more like industrial hygiene than the other states, which makes it more rigorous for heavy manufacturing and more technical to get right.

If your Minnesota work involves real physical exertion, WBGT monitoring equipment is not optional. A standard thermometer will not satisfy the standard.

What must a written heat illness prevention plan actually contain?

Across all five state standards, a heat illness prevention plan consistently needs to cover seven core elements. The exact wording and documentation depth vary by state, but cover these and you're close to compliance with any of them.

1. Heat monitoring. Who measures temperature or WBGT, what instrument they use, how often, and what records they keep.

2. Water and shade or cooling access. Specific quantities (usually 1 quart per person per hour), locations, and how access gets communicated to workers.

3. Rest break procedures. Frequency, duration, and location of cool-down rest, including preventive rest before symptoms show up.

4. Acclimatization schedule. A written ramp-up schedule for new employees and workers returning after an absence during a heat wave. Most standards call for a 7 to 14 day acclimatization period with reduced initial workloads.

5. Symptom recognition and response. Signs of heat cramps, heat exhaustion, and heat stroke, who is trained to recognize them, and what to do including calling 911.

6. Emergency response contacts. On-site first aid resources, nearest emergency room, and how supervisors signal an emergency to everyone on site.

7. Training records. Documentation that workers and supervisors got heat illness training before working in heat-exposed conditions.

Your plan should be a living document, not a PDF you file and forget. Update it when job tasks change, when you open new locations, when you add indoor operations, or when state rules get amended. A well-built written program is the foundation here.

Want a fast starting point? SafetyFolio's safety program generator can produce a state-matched heat illness prevention plan draft in about 15 minutes, which you then review and sign.

What are the penalties for not having a written heat plan?

Penalty amounts depend on the state and the violation classification. Here is a realistic range based on published penalty schedules.

California: serious violations carry penalties up to $15,625 per violation. Willful or repeat violations go up to $156,259 per violation ^[3]. Cal/OSHA has issued multi-citation cases involving heat deaths where total proposed penalties topped $100,000.

Oregon: serious violations carry penalties up to $14,502 per violation as of 2024 ^[5]. Willful violations can reach $145,027.

Washington: serious violations carry penalties up to $7,000 per day per violation for ongoing hazards ^[6].

Colorado: serious violations carry penalties up to $15,625 per violation, mirroring the federal schedule ^[7].

The fine is the smaller problem. A heat-related fatality triggers an OSHA fatality investigation, mandatory reporting within 8 hours under 29 CFR 1904.39, and potential referral for criminal prosecution in egregious cases ^[9]. The employer also faces workers' compensation claims and civil litigation. The written plan itself is often the first document a state OSHA inspector asks for after a heat illness hospitalization or death. Not having one is an immediate red flag.

Here's the scale of the problem. The Bureau of Labor Statistics recorded 36 work-related heat stroke deaths in 2021 and 43 in 2022, with thousands more heat illness hospitalizations every year ^[10].

Does the plan need to be in a language other than English?

Yes in California, and practically yes everywhere else. California's 8 CCR § 3395 explicitly requires the written plan to be in English and in the language understood by the majority of workers at the site ^[3]. If most of your crew speaks Spanish, you need a Spanish-language plan. Mixed workforce? You may need both.

Oregon's rule does not mandate a specific non-English translation in the regulation text, but OR-OSHA's worker rights regulation (OAR 437-001-0700) requires that training be provided in a language workers understand ^[5]. In practice, inspectors treat a plan workers cannot read as an ineffective plan.

Washington and Colorado have similar comprehension requirements. The safe approach is to translate your written plan into any language spoken by 10% or more of your workforce. Federal OSHA's website has heat illness materials in Spanish, and Cal/OSHA publishes bilingual templates.

What if I operate in multiple states with different rules?

You need to know which standard applies at each location. Federal OSHA covers workers in the 24 states and territories without state-plan programs. State OSHA agencies cover everyone else, including federal contractors in state-plan states (with some exceptions for specific federal contract types).

The practical move for multi-state employers is to build your plan to the most stringent standard across your locations, then note state-specific deviations. California's combined indoor and outdoor standards are currently the most demanding. If your plan satisfies California, you're almost certainly compliant in Oregon, Washington, and Colorado too. Minnesota is different enough (WBGT-based) that it needs its own section or addendum.

Keep a version-controlled master document with a clear notation of which state each section satisfies. When a state inspector asks whether your plan meets their specific regulation, point to the relevant section directly.

For background on how state-plan OSHA programs differ from federal, see what does OSHA stand for for a quick orientation, and the OSHA training article for how your state-specific training obligations tie in.

How does the proposed federal OSHA heat rule change everything?

OSHA's proposed Heat Injury and Illness Prevention rule, published August 30, 2024 ^[1], would create a federal floor that applies in all 50 states. State-plan states would then have to adopt a standard at least as protective as the federal rule within 6 months of its final publication.

The proposed federal rule sets two trigger temperatures: an initial heat trigger at 80°F and a high heat trigger at 90°F. At the initial trigger, employers would provide water, rest, and shade and maintain a written HIIPP. At the high heat trigger, employers would add mandatory rest breaks (15 minutes minimum every 2 hours), a heat monitoring buddy system, and mandatory acclimatization schedules.

The proposed rule's written plan requirement runs more detailed than most current state standards. It specifically requires a hazard identification section that maps heat sources at each work area, not a generic policy. Employers with fewer than 10 employees would get some simplified documentation options, but they would not be exempt from the written plan requirement.

This rule is not final. The comment period closed in late 2024, and the agency is reviewing responses. Regulatory timelines shift, especially across administration changes. Watching the OSHA regulatory agenda page (www.osha.gov) for updates is the best way to track this one in real time.

Regardless of when the federal rule finalizes, building a written plan now to the proposed standard is smart risk management. If the rule passes, you're ready. If it does not, you still have documentation that shows OSHA you recognized and addressed the hazard, which matters under a General Duty Clause defense.

How do you train workers and supervisors on the heat plan?

Every state standard requires training before workers are exposed to heat-related conditions, not after an incident. Supervisor training and worker training carry different content requirements.

Workers need to know: the signs and symptoms of heat cramps, heat exhaustion, and heat stroke; how to reach water and shade; their right to request a preventive cool-down rest period without retaliation; how to report symptoms; and who to contact in an emergency.

Supervisors need all of that plus how to monitor weather and worksite conditions, how to run the acclimatization schedule for new hires, how to recognize when a worker needs emergency help (heat stroke means calling 911, more than moving someone to shade), and their authority to stop work when conditions turn dangerous.

Training records should document the date, the trainer's name, the topics covered, and each employee's name and signature. Keep those records for at least one year in a format you can pull up fast during an inspection.

For broader context on OSHA training documentation, the OSHA 30 training article covers how to structure training recordkeeping across multiple programs at once. If your supervisors oversee both heat exposure and equipment operation, coordinating their training documentation in one system saves real time.

SafetyFolio's safety program generator includes a built-in training log template alongside the plan document, so you're not building those two pieces separately.

What should I do right now if I don't have a written plan?

Start with where you operate. If you're in California, Oregon, Washington, Colorado, or Minnesota, you're legally required to have a written plan before your workers are exposed to heat at the trigger temperatures. "We're working on it" is not a defense when an inspector walks in on a 90-degree day.

If you're in a federal OSHA state, you have no specific written plan mandate yet, but the General Duty Clause still applies. A written plan is your strongest evidence that you recognized the hazard and controlled it. Write one anyway.

Here is the fastest legitimate path. Download your state's free template (California, Oregon, and Washington all publish them). Fill in your specific worksite information, the names of your designated heat safety monitor and emergency contacts, and your water and rest procedures. Have your most experienced supervisor review it for accuracy. Translate it if needed. Sign and date it. Post a notice to workers that the plan exists and where to find it. Train your team before the next hot day.

Done honestly, that takes a few hours the first time. After that, you review and update it annually before heat season begins. An incident report system tied to your heat plan makes sure any close calls or minor illnesses get documented, which helps you catch patterns before a serious injury lands.

Don't miss the hazard communication obligations that can overlap with heat when your workers handle chemicals that get more hazardous at elevated temperatures. Many employers miss that connection.

Frequently asked questions

Is a written heat illness prevention plan required by federal OSHA right now?

No final federal standard requiring a written heat plan exists as of mid-2025. Federal OSHA proposed one on August 30, 2024, but it has not been finalized. Federal OSHA currently enforces heat hazards through the General Duty Clause. State-plan states including California, Oregon, Washington, Colorado, and Minnesota all have enforceable written plan requirements already.

What temperature triggers the written plan requirement in California?

California's outdoor heat standard at 8 CCR § 3395 requires a written plan whenever workers are exposed to outdoor temperatures at or above 80°F. The 2024 indoor heat rule requires a separate indoor plan when indoor temperatures reach 82°F. Both thresholds run on ambient air temperature, not heat index.

Does the heat illness prevention plan have to be in Spanish?

In California, yes, the plan must be in English and in the language understood by the majority of workers. If most workers speak Spanish, the plan must be in Spanish. Other state standards (Oregon, Washington, Colorado) lack identical explicit language requirements in the regulation text, but inspectors treat an unreadable plan as an ineffective one. Translating the plan is the safe move everywhere.

How often do I need to update my heat illness prevention plan?

None of the five state standards sets a specific annual review deadline, but best practice (and what inspectors look for) is a review before each heat season. Update the plan whenever a designated monitor changes, when you open a new worksite, when you add indoor operations, or when state rules get amended. Date and sign each revision so you have a clear history.

Does the heat illness plan cover indoor workers?

It depends on the state. California added an indoor heat rule in 2024 covering most workplaces at 82°F. Colorado's rule covers all industries indoors and outdoors at 80°F. Oregon and Washington both cover indoor workers. Minnesota's WBGT-based standard applies wherever heat stress occurs, including indoors. Federal OSHA's proposed rule would cover both environments.

Can I use a template I found online, or does the plan need to be custom?

Templates from your state OSHA agency are a legitimate starting point, and using them is no compliance shortcut. The failure happens when employers fill in a template generically and never adapt it to their actual worksite. Inspectors check that the plan names your actual water sources, rest areas, and emergency contacts. A template with real, site-specific information filled in correctly is perfectly acceptable.

What's the difference between a heat illness prevention plan and a heat stress program?

The terms get used interchangeably, but "heat stress program" tends to be the broader occupational health label while "heat illness prevention plan" is the specific document required by state OSHA regulations. Your written plan is the core document. A heat stress program may also include engineering controls documentation, PPE selection records, medical surveillance, and monitoring logs that sit alongside the plan.

Do I need a separate heat plan for each jobsite, or can one plan cover multiple locations?

California's standard requires the plan to be at the worksite and available to employees, which implies site-specific information. In practice, a master plan works if it includes site-specific appendices covering each location's water sources, shade locations, emergency contacts, and nearest hospital. A single document with blank fields is not acceptable. Each location's section must carry real, filled-in information.

What records do I need to keep related to the heat plan?

At a minimum, keep the signed and dated written plan itself, training records showing who was trained and when, heat monitoring logs (temperatures recorded during hot days), and any records of cool-down rest periods taken by workers. Colorado explicitly requires retention of heat monitoring measurement records. Oregon requires documentation of who the designated monitor is. Keep these records for at least one year.

How does the proposed federal heat rule affect states that already have their own standards?

Under the OSH Act, state-plan states must adopt a standard at least as protective as the federal standard within 6 months of its finalization. States whose existing standards are already more protective (like California) can keep their current rules. States whose rules are less stringent would need to amend them. The federal rule creates a nationwide floor, not a ceiling.

Are agricultural workers covered by heat illness prevention plans?

Yes. Agricultural workers were actually the first group covered by state heat rules. California's original 2005 standard focused heavily on farmworkers. Oregon and Washington both cover agricultural operations. The proposed federal rule covers agriculture as well as general industry and construction. Some federal agricultural OSHA standards have narrower coverage, so check whether your farm workers fall under federal or state jurisdiction.

What happens during an OSHA inspection if my heat plan is missing or incomplete?

In a state with a written plan requirement, a missing plan is a citable serious violation. An incomplete plan (missing acclimatization procedures, no emergency contacts, no language translation) can also draw a serious violation. Inspectors typically request the written plan within the first 30 minutes of an inspection. If you cannot produce one, expect a citation with penalties ranging from a few thousand dollars to over $15,000 per violation depending on the state.

Does a small business with fewer than 10 employees need a written heat illness prevention plan?

Yes, in all five states with heat standards, the written plan requirement applies regardless of employer size. There is no small-employer exemption for heat plans in California, Oregon, Washington, Colorado, or Minnesota. The proposed federal rule mentions simplified documentation for small employers but does not exempt them. Size matters for some penalty reductions after a citation, not for the obligation itself.

Sources

1. OSHA, Federal Register: Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings (proposed rule), Aug. 30, 2024: Federal OSHA published a proposed heat illness prevention rule on August 30, 2024, establishing initial heat trigger at 80°F and high heat trigger at 90°F, with a written HIIPP requirement.
2. OSHA, OSH Act Section 5(a)(1), General Duty Clause: OSHA enforces heat hazards through the General Duty Clause, which requires employers to protect workers from recognized serious hazards even without a specific standard.
3. California Department of Industrial Relations, Cal/OSHA Heat Illness Prevention standard, 8 CCR § 3395: California's outdoor heat illness prevention standard requires a written plan in English and the language of the majority of workers, covering water, shade, rest, acclimatization, and emergency procedures; serious violations carry penalties up to $15,625 and willful violations up to $156,259.
4. California Department of Industrial Relations, Cal/OSHA Indoor Heat Illness Prevention standard (effective July 2024): California's 2024 indoor heat rule requires a separate written Indoor Heat Illness Prevention Plan when indoor temperatures reach 82°F.
5. Oregon OSHA, Heat Illness Prevention standard, OAR 437-002-0156: Oregon's heat rule took effect June 15, 2022, triggers at 80°F for indoor and outdoor work, requires a written plan including designated monitors and emergency procedures, and carries serious violation penalties up to $14,502.
6. Colorado Department of Labor and Employment, OSHA Division, Heat Illness Prevention rule, 7 CCR 1101-5 (effective May 1, 2023): Colorado's heat rule applies to all industries at 80°F indoors and outdoors, requires a written plan with heat monitoring protocols, and covers warehouse, kitchen, laundry, and manufacturing workers.
7. Minnesota Department of Labor and Industry, MNOSHA Indoor Heat Exposure standard, MNOSHA 5205.0110: Minnesota's heat standard uses Wet Bulb Globe Temperature with a lowest action level of about 77°F for heavy work and requires a written plan identifying heat sources and control measures.
8. OSHA, Injury and Illness Recordkeeping and Reporting Requirements, 29 CFR 1904.39: A heat-related fatality requires employer reporting to OSHA within 8 hours under 29 CFR 1904.39.
9. Bureau of Labor Statistics, Census of Fatal Occupational Injuries, Heat-related deaths 2021-2022: BLS recorded 36 work-related heat stroke deaths in 2021 and 43 in 2022, with thousands more heat illness hospitalizations annually.
10. OSHA, State Plans overview: State-plan states operate OSHA-approved programs covering public and private sector workers and can adopt standards more stringent than the federal baseline.