Which states require a written heat illness prevention plan?
For a construction contractor, only 5 states require a written heat illness prevention plan: California, Oregon, Washington, Nevada, and Maryland. Coverage often reported as 7 states folds in Colorado, whose rule covers agriculture only, and Minnesota, a 1997 indoor-temperature rule. Everywhere else, a written plan is enforced through OSHA's General Duty Clause and its Heat National Emphasis Program, in effect through April 2031.
Last verified: 2026-07-07 against primary and agency sources.
State heat rules at a glance
The 7 states below have adopted a workplace heat rule. Only the first five create a written-plan obligation for a general or construction contractor; Colorado and Minnesota are limited in scope, noted in the coverage column.
| State | Written plan for contractors? | Rule | Coverage | In effect since |
|---|---|---|---|---|
| California | Yes | 8 CCR 3395 (outdoor), 3396 (indoor) | Indoor and outdoor | Outdoor 2006 (amended 2015); indoor (3396) July 23, 2024 |
| Maryland | Yes | COMAR 09.12.32 | Indoor and outdoor | September 30, 2024 |
| Nevada | Yes | NAC 618 (R131-24) | All employers with more than 10 employees (climate-controlled indoor exempt) | April 29, 2025 |
| Oregon | Yes | OAR 437-002-0156 | Indoor and outdoor (separate agriculture rule) | June 15, 2022 |
| Washington | Yes | WAC 296-62-095 | Outdoor (year-round) | July 17, 2023 (permanent rule) |
| Colorado | No | 7 CCR 1103-15 | Agriculture only (all-industry expansion pending) | May 1, 2022 (amended February 1, 2026) |
| Minnesota | No | Minn. R. 5205.0110 | Indoor temperature and ventilation | 1997 |
What each state requires
- California full requirements
- 8 CCR 3395: shade and cool-down rest at 80°F outdoors, high-heat procedures at 95°F. Water and training required at all times. Indoor rule (3396) starts at 82°F.
- Maryland full requirements
- COMAR 09.12.32: written plan, water (32 oz/hr), shade, and acclimatization (up to 14 days) at heat index 80°F; high-heat procedures and monitoring at heat index 90°F.
- Nevada full requirements
- R131-24 (NAC ch. 618): no temperature trigger. Employers with more than 10 employees must do a written heat job hazard analysis and keep a written plan where exposure exceeds 30 minutes in any 60-minute period.
- Oregon full requirements
- OAR 437-002-0156: shade and water at heat index 80°F; written rest-break schedule, acclimatization plan, and emergency plan at heat index 90°F.
- Washington full requirements
- WAC 296-62-095: applies year-round at 80°F (52°F in non-breathable clothing); paid cool-down rest of 10 min every 2 hours at 90°F, 15 min every hour at 100°F.
- Colorado full requirements
- Colorado requires a written heat plan only of agricultural employers today. HB 26-1272, signed June 4, 2026, expands protections to all industries on a phased basis, so a construction crew still falls under the federal framework until that takes effect.
- Minnesota full requirements
- Minnesota sets indoor workplace temperature limits (about 68 to 77 degrees F for light office work), a comfort and ventilation rule rather than a heat illness prevention plan, so it does not create an outdoor construction plan obligation.
States with heat rules on the way
More states are adopting or expanding heat rules. We update this list as each one moves.
| State | What is happening | Expected |
|---|---|---|
| Virginia | Heat illness bills signed April 13, 2026; Safety and Health Codes Board directed to write indoor and outdoor standards. | Standard due by May 1, 2028 |
| Colorado (expansion) | HB 26-1272, signed June 4, 2026, extends heat protections beyond agriculture to all indoor and outdoor workers. | Data collection 2027; written plans by 2028 |
| New Mexico | Formal rulemaking underway to create a mandatory heat illness prevention rule. | In progress |
| Illinois | In the rulemaking process to propose a permanent heat illness prevention regulation. | In progress |
| Arizona | In the rulemaking process to propose a permanent heat illness prevention regulation. | In progress |
How this was compiled
Each entry is drawn from the state's own regulation and agency guidance, cross-checked against OSHA's list of state heat standards and the National Resources Defense Council's occupational heat tracker, and dated to when the current rule took effect. This is a compliance reference for contractors, not legal advice; confirm the current rule with the state agency before you rely on it.
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Common questions
▸Which states require a written heat illness prevention plan for contractors?
Five: California (8 CCR 3395 outdoor and 3396 indoor), Oregon (OAR 437-002-0156), Washington (WAC 296-62-095), Nevada (NAC 618, employers over 10 employees), and Maryland (COMAR 09.12.32). Coverage often reported as six or seven states folds in Colorado, whose rule covers agriculture only, and Minnesota, a 1997 indoor-temperature rule.
▸Does Colorado require a heat plan for construction?
Not yet. Colorado 7 CCR 1103-15 has required a written heat plan of agricultural employers since 2022. HB 26-1272, signed June 4, 2026, expands protections to all industries on a phased basis, so a construction crew still falls under the federal framework until that takes effect.
▸What about states with no heat rule?
Federal OSHA still applies. It cites excessive heat under the General Duty Clause and inspects proactively under its Heat National Emphasis Program, renewed in April 2026 and in effect through April 2031. Heat inspections have risen roughly twelvefold in recent years, so a written plan is a practical necessity even where no state rule exists.
▸What must the written plan contain?
Every state rule expects the same core: drinking water, shade or cooling, paid cool-down rest, acclimatization for new and returning workers, emergency response, training, and written procedures. The specific triggers and rest schedules vary by state; the per-state pages list each one with its citation.
Official sources
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