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State Heat-Illness Bills Reshape WC Frequency Before OSHA Acts

At least five states have filed heat-illness prevention bills in 2026, creating mandatory documentation and presumption provisions that expand the universe of reportable WC claims while OSHA's federal heat rule remains stalled.

By Sam, EditorJune 2026 · 3 min read

NCCI’s 2026 Emerging Legislative and Regulatory Issues report identifies heat exposure as one of three top emerging WC legislative themes, citing roughly 34,000 heat-related workplace injuries and 479 fatalities between 2011 and 2022. While OSHA’s proposed federal heat standard remains stalled with no finalization date, at least five states have advanced bills in 2026 that would create new documentation requirements, temperature triggers, and compensability standards for heat-related claims.

Arizona’s HB 2684 would require employers to develop written heat-illness mitigation programs whenever workplace temperatures reach 80 degrees Fahrenheit. The bill mandates free drinking water near worksites, preventive cool-down rest periods, ambient temperature monitoring with thermometers, and annual plan updates. New Hampshire’s HB 1451 goes further, establishing the Workplace Extreme Temperatures Protection Standards Act covering both heat and cold exposure with written plans, training programs, and emergency protocols.

California’s AB 1336, vetoed last year, would have created a disputable presumption for agricultural heat injuries when employers failed to comply with existing prevention standards. That model is now circulating in other legislatures. When a presumption provision passes, the burden of proof shifts from the claimant to the employer, raising the rate of allowed claims without any change in underlying incidence.

At the federal level, the Asuncion Valdivia Heat Illness Prevention Act (S. 2298) would require OSHA to promulgate a permanent heat standard, bypassing the stalled rulemaking. OSHA published its proposed rule in August 2024, completed public comment by October 2025, and has set no date for finalization. The agency’s renewed Heat National Emphasis Program provides enforcement tools through 2031 but does not create the binding employer obligations a final rule would carry.

Who It Affects

Self-insured employers in construction, agriculture, landscaping, warehousing, and outdoor maintenance, particularly in Sun Belt and mid-Atlantic states where summer heat indices routinely exceed 80 degrees. Public entities with outdoor crews, parks departments, and transit operations carry the same exposure. The coverage line is workers’ compensation indemnity and medical benefits for heat stroke, heat exhaustion, and rhabdomyolysis.

The Reserve Mechanism

The primary mechanism is frequency expansion. Mandatory documentation requirements (written mitigation plans, temperature logs, rest break records) convert previously unreported heat events into formal WC claims with a paper trail. The 80-degree threshold in Arizona’s bill would capture most outdoor summer workdays, creating a continuous documentation obligation that makes it far easier for employees to establish a work connection.

Presumption provisions amplify the effect. If other states adopt California’s AB 1336 template, the compensability gate widens: employers must disprove the work connection rather than claimants proving it. For self-insured programs, this translates to a discrete frequency adjustment in affected jurisdictions that sits on top of the existing development pattern.

Expected claim ratios for outdoor exposure classes should be re-examined. Self-insureds benchmarking to pre-2022 heat claim data are likely understating the frequency component because earlier numbers reflect an era before documentation mandates existed.

What This Means for Your Next Review

Ask your actuary whether your WC frequency assumption includes a discrete loading for heat-illness claims in states where new documentation or presumption requirements are pending or enacted. If your program operates in multiple states, confirm the TPA’s data extract flags state of jurisdiction at the claim level so heat-related experience in affected states can be isolated and tracked separately from the aggregate triangle.

Sources

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