OSHA’s outdoor temperature regulations do not set a specific temperature at which outdoor work must stop, in either heat or cold. Instead, federal OSHA enforces temperature safety through the General Duty Clause of the Occupational Safety and Health Act of 1970, which requires every employer to keep the workplace free of recognized hazards likely to cause death or serious physical harm.1Occupational Safety and Health Administration. OSH Act of 1970 – Section 5 Duties That clause is backed by detailed guidance, an active inspection program aimed at heat hazards, and penalties that can reach six figures per violation. A handful of states have gone further and adopted enforceable heat rules with specific temperature triggers.
No Federal Cutoff Temperature
Federal OSHA does not set a maximum outdoor temperature at which work must stop, and does not require break schedules tied to a thermometer reading.2Occupational Safety and Health Administration. Heat – Standards The same is true for cold: no federal wind chill cutoff and no mandated warm-up breaks.3Occupational Safety and Health Administration. Winter Weather – Cold Stress The absence surprises many workers and employers, but it does not mean OSHA lacks authority. The General Duty Clause makes it illegal for an employer to expose workers to a recognized hazard, including extreme temperatures, when a feasible way to reduce the risk exists.
An employer cannot defend itself by pointing to the missing regulation. To cite under the General Duty Clause for a heat or cold hazard, OSHA has to show the workplace contained a recognized hazard likely to cause death or serious physical harm and that a feasible abatement method existed. Courts have upheld this approach in heat cases.
How OSHA Enforces Heat Hazards
OSHA runs a National Emphasis Program on outdoor and indoor heat-related hazards, originally launched in April 2022 and extended through April 8, 2026. On any day the National Weather Service issues a heat warning or advisory, inspectors can conduct pre-planned inspections of high-risk worksites in over 70 targeted industries. Between April 2022 and December 2024, OSHA conducted roughly 7,000 heat-related inspections, investigated 147 heat-related fatalities, issued 60 General Duty Clause citations, and sent 1,392 Hazard Alert Letters warning employers to correct conditions before a formal citation.4OSHA. Extension of CPL 03-00-024, National Emphasis Program – Outdoor and Indoor Heat-Related Hazards
The program designates “heat priority days” whenever the heat index is expected to reach 80°F or higher. On those days, OSHA increases outreach in targeted industries and continues to investigate any reported heat-related fatality, hospitalization, complaint, or referral, regardless of industry.5OSHA. OSHA National Emphasis Program on Outdoor and Indoor Heat Hazards For measuring the actual hazard, OSHA relies on Wet Bulb Globe Temperature rather than a plain thermometer, because WBGT accounts for humidity, radiant heat from sunlight, and wind speed in a single reading.6Occupational Safety and Health Administration. Heat – Heat Hazard Recognition
What Employers Are Expected to Provide
OSHA’s “Water. Rest. Shade.” guidance describes what a compliant heat program looks like. It uses “should” language because it is not a regulation, but an employer who ignores it will have a hard time defending a General Duty Clause citation, because the guidance itself demonstrates that feasible protections exist.7Occupational Safety and Health Administration. Heat – Water. Rest. Shade.
- Cool drinking water, with workers encouraged to drink at least 8 ounces every 20 minutes even when not thirsty. For jobs lasting more than two hours, electrolyte beverages should also be available.
- Frequent rest breaks in a location that allows the body to cool, with break length and frequency rising as heat stress rises.
- A shaded area close to the worksite that is large enough to fit every resting worker at once.
Training on the symptoms of heat illness belongs on the same list. Workers who cannot recognize the early signs, including heavy sweating that suddenly stops, confusion, slurred speech, and loss of consciousness, are the ones most likely to die from exposure. Every site with temperature-exposure risk should have a written emergency response plan that workers know before they need it.
Acclimatization Is Where Most Tragedies Happen
Workers new to a job, or returning after a week or more away, have not yet adapted to the heat and face a much higher risk of heat illness. OSHA and NIOSH both recommend a gradual exposure schedule that builds tolerance over 7 to 14 days.8Occupational Safety and Health Administration. Heat – Protecting New Workers
For workers with no prior heat exposure, OSHA recommends the “Rule of 20 Percent”: work only 20 percent of the normal duration on day one, and increase by no more than 20 percent each additional day, reaching full workload by the end of the first week. Workers who already have experience with the job can follow a faster schedule: 50 percent on day one, 60 percent on day two, 80 percent on day three, and full duty by day four.9Centers for Disease Control and Prevention. Acclimatization – Heat Stress
One detail gets missed often. Acclimatization means reducing the duration of work in the heat, not the intensity. A new worker hired to do heavy outdoor labor should perform that same heavy labor during acclimatization, just for shorter periods. Assigning light tasks during the first week will not build the tolerance the actual job requires.
Cold-Weather Obligations
OSHA treats cold the same way it treats heat under the General Duty Clause: employers must protect workers from recognized cold hazards like hypothermia, frostbite, and trench foot.10Occupational Safety and Health Administration. Cold Stress Guide No specific federal wind chill threshold triggers mandatory action. OSHA directs employers to monitor NOAA weather alerts and treat Wind Chill Warnings and Advisories as signals to increase protections. A 35°F reading can be misleading once sustained wind drops the effective temperature into dangerous territory.
Expected protections include radiant heaters and windbreaks at outdoor workstations, scheduling demanding tasks during the warmest hours, rotating workers between cold and warm environments, running a buddy system so workers watch each other for early symptoms like shivering or confusion, and providing frequent short breaks in heated areas. OSHA also recommends at least three layers of loose-fitting clothing, along with insulated waterproof gloves and boots and a hat that covers the ears.11Occupational Safety and Health Administration. Winter Weather – Preparedness
States That Go Further Than Federal OSHA
Several states run their own OSHA-approved safety programs and have adopted enforceable heat illness prevention standards that go beyond federal guidance. As of 2026, at least seven states have specific heat regulations on the books.2Occupational Safety and Health Administration. Heat – Standards Some cover only outdoor work, others cover both indoor and outdoor environments, and at least one applies specifically to agriculture.
The typical state standard uses a temperature trigger, often 80°F, that activates the employer’s duties: drinking water, shade or other cooling, and a written heat illness prevention plan. A higher trigger, commonly around 90°F, adds mandatory paid cool-down breaks and closer monitoring of workers showing symptoms. State standards also commonly require a formal acclimatization period, mandatory training, and immediate access to emergency medical services. In these states, an employer is cited for a specific regulatory violation rather than under the broader General Duty Clause, which makes enforcement easier and penalties harder to contest.
The Proposed Federal Heat Standard Is Frozen
In August 2024, OSHA published a Notice of Proposed Rulemaking for a federal heat injury and illness prevention standard covering general industry, construction, maritime, and agricultural employers under OSHA jurisdiction.12Occupational Safety and Health Administration. Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings Rulemaking The proposed rule defined two trigger levels: an initial heat trigger at a heat index of 80°F, and a high heat trigger at 90°F.13OSHA. Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings – Proposed Regulatory Text Employers would have been required to create written heat safety plans, evaluate workplace conditions, and take escalating protective steps as temperatures rose.
A government-wide regulatory freeze issued in January 2025 halted the rulemaking before it could be finalized. As of mid-2025, the proposal has not been withdrawn or officially terminated, but no timeline exists for it to move forward. Until then, federal enforcement runs on the General Duty Clause, OSHA guidance, the active National Emphasis Program, and any state standard that applies.
What Workers Can Do
If you believe your employer is exposing you to dangerous heat or cold without adequate protection, you can file a confidential complaint with OSHA online, by phone, or by mail, and OSHA is required to investigate. Your employer is not permitted to learn from OSHA who filed the complaint.14Occupational Safety and Health Administration. File a Complaint
You may also have the right to refuse dangerous work, but the conditions are strict. All of the following must be true: you genuinely believe the condition poses a real danger of death or serious injury, a reasonable person would agree with that assessment, you asked your employer to correct the hazard and the employer did not act, and the danger is so urgent that there is not enough time for OSHA to inspect.15Occupational Safety and Health Administration. Workers’ Right to Refuse Dangerous Work Being uncomfortable in the heat does not qualify. A 110°F heat index with no water, no shade, and a coworker already showing symptoms of heat stroke would.
If your employer retaliates for reporting a safety concern or refusing dangerous work, you can file a whistleblower complaint under Section 11(c) of the OSH Act. The deadline is short: 30 days from the retaliation.16Whistleblowers.gov. Occupational Safety and Health Act (OSH Act), Section 11(c)
Employer Reporting Duties and Penalties
When a temperature-related incident causes a fatality, the employer must report it to OSHA within 8 hours. An in-patient hospitalization must be reported within 24 hours. Both deadlines run from when the employer learns of the event, not from when it happens.17Occupational Safety and Health Administration. Reporting Fatalities, Hospitalizations, Amputations, and Losses of an Eye as a Result of Work-Related Incidents to OSHA
OSHA penalties are adjusted annually for inflation. As of 2025, the maximum fine for a serious violation is $16,550 per violation, and the maximum for a willful or repeated violation is $165,514 per violation.18Occupational Safety and Health Administration. 2025 Annual Adjustments to OSHA Civil Penalties A single heat inspection that uncovers multiple failures, like no water, no shade, no training, and no acclimatization plan, can produce separate citations that stack. Willful violations, where OSHA finds the employer knew about the hazard and chose to ignore it, carry the highest penalties and can trigger referrals for criminal prosecution when a worker dies.