Heat Illness Prevention Rules by State
With no federal heat standard in force, 7 states have adopted their own enforceable rules. Here's what each requires — and what applies everywhere else.
Part of our Heat Illness Prevention guide.
| State | Scope | What it requires |
|---|---|---|
| California(CA) | Outdoor & indoor | Cal/OSHA's outdoor heat standard requires water, shade at 80°F, rest, and acclimatization; a separate indoor heat standard took effect in 2024 for most indoor workplaces. Cal/OSHA — Heat Illness Prevention ↗ |
| Colorado(CO) | Agricultural workers | Colorado rules adopted under SB 21-087 extend heat protections — including rest, shade, and water — to agricultural workers. Colorado Dept. of Labor & Employment — Agricultural Labor ↗ |
| Maryland(MD) | Outdoor & indoor | Maryland MOSH adopted a heat stress standard (effective 2024) requiring a heat illness prevention plan, water, rest, shade, and acclimatization. Maryland MOSH — Heat Stress Standard ↗ |
| Minnesota(MN) | Indoor | Minnesota OSHA enforces an indoor heat standard setting maximum workplace temperatures based on workload (Minn. Rules 5205.0110). Minnesota OSHA — Indoor Heat ↗ |
| Nevada(NV) | Most employers (>10 employees) | Nevada adopted a heat illness regulation (2024) requiring covered employers to maintain a written safety program addressing heat hazards. Nevada OSHA — Heat Illness ↗ |
| Oregon(OR) | Outdoor & indoor | Oregon OSHA's heat rules require access to shade and water at 80°F and additional measures (rest, communication, emergency plans) at 90°F. Oregon OSHA — Heat ↗ |
| Washington(WA) | Outdoor | Washington L&I's outdoor heat-exposure rules require water, shade, paid cool-down rest, and acclimatization, with triggers beginning at 80°F. Washington L&I — Outdoor Heat ↗ |
Every other state
No state-specific heat standard. OSHA enforces heat hazards under the General Duty Clause (Section 5(a)(1)) and the Heat National Emphasis Program. Employers should still provide water, rest, shade, acclimatization, and training. OSHA — Heat ↗
Frequently Asked Questions
As of 2026, 7 states have adopted their own enforceable heat standards: California, Colorado, Maryland, Minnesota, Nevada, Oregon, and Washington. The specifics — scope, trigger temperatures, and covered workers — vary by state.
Not yet. OSHA published a proposed heat rule in 2024, but until it is finalized, federal OSHA enforces heat hazards under the General Duty Clause and a Heat National Emphasis Program.
Federal OSHA applies. Employers should still provide water, rest, shade, acclimatization for new workers, and training — the measures OSHA uses to evaluate heat hazards under the General Duty Clause.