
Seyfarth Synopsis: On August 14, 2026, Cal/OSHA released a revised discussion draft of proposed changes to California’s heat illness prevention standards included in Section 3395 (Outdoor Heat Illness Prevention) and Section 3396 (Indoor Heat Illness Prevention). The proposal continues Cal/OSHA’s effort to implement AB 2243, which was signed into law in 2022, while making California’s indoor and outdoor heat standards more consistent in structure and terminology. Although many of the revisions are intended to harmonize the two standards, the draft also contains substantive changes that could significantly affect compliance obligations, including an expansion of outdoor high-heat procedures and new acclimatization requirements for newly-assigned and returning employees. Comments on the discussion draft are due September 21, 2026. Some like it hot—but Seyfarth is here to prepare employers for the rising temperatures. Keep reading for everything employers need to know about the August 2026 draft.
Background
It’s been a long, hot summer, or really summers, as Cal/OSHA continues to modify its proposed revisions to California’s heat illness prevention regulations. As we previously discussed, in May 2025, Cal/OSHA released its first proposed revisions as part of its effort to implement AB 2243. Among other things, AB 2243 directed Cal/OSHA to consider revisions relating to heat illness prevention plans and acclimatization requirements. Although AB 2243 focused primarily on the outdoor heat standard, Cal/OSHA elected to review both the outdoor and indoor regulations. Following stakeholder comments and advisory committee discussions, Cal/OSHA released a substantially revised draft on August 14, 2026.
It’s Getting Hot Out There: Expanded Outdoor High-Heat Procedures
Perhaps the most scorching proposal in the August 2026 draft is the elimination of an existing limitation on Section 3395’s outdoor high-heat procedures, which currently only apply to employers in specified industries, including agriculture, construction, landscaping, oil and gas extraction, and certain transportation operations. The August 2026 proposal extends high-heat requirements to a broad range of outdoor employers whenever temperatures reach 95 degrees Fahrenheit. For employers previously not subject to California’s high-heat requirements, this change could have a significant practical impact.
Soak Up the Sun (Slowly): Expanded Acclimatization Requirements
The August 2026 proposal adds more well-defined acclimatization requirements. Under California’s current regulations, employers must closely observe newly assigned employees during specified periods of elevated heat exposure. The August 2026 draft retains and expands concepts first introduced in the May 2025 proposal by addressing both newly assigned employees and employees returning to work after an absence exceeding 14 days.
Under the proposal, employers would have two options when assigning unacclimatized employees to covered heat conditions. Employers could:
- Implement enhanced protective measures and close observation procedures; or
- Phase employees into heat exposure through prescribed exposure schedules.
California isn’t walking on the sun alone. The proposed changes mirror acclimatization provisions in Oregon’s heat illness rule as well as federal OSHA’s proposed heat illness rule.
Although the precise details may continue to evolve during the rulemaking process, the broader message from Cal/OSHA is clear: employers should anticipate greater scrutiny of acclimatization practices.
Clear Instructions Even During a Cruel Summer: Distribution of Heat Illness Prevention Plans
The August 2026 draft retains one of the most notable additions from the May 2025 proposal: affirmative requirements for distributing Heat Illness Prevention Plans (HIPPs).
Cal/OSHA wants every employee to have their own pocketful of sunshine—a HIPP within arm’s reach. Under the proposed language, employers would be required to distribute HIPPs to employees upon hire, during heat illness prevention training, and at least once annually. The proposal clarifies that employers would not be required to distribute the plan to the same employee more than twice each year and would permit electronic posting and distribution in certain circumstances.
Heating Up The Focus on Heat Illness Recognition
The August 2026 draft also continues Cal/OSHA’s effort to align definitions and terminology between the indoor and outdoor standards. Among other changes, the proposal includes rhabdomyolysis within the definition of heat illness, adds supplements and recreational drugs to the list of personal risk factors, and creates a more detailed and consistent description of heat illness signs and symptoms across both regulations. Although these revisions may not dramatically alter day-to-day compliance obligations, employers may ultimately need to update training materials, written programs, and educational resources if the August 2026 proposal moves forward substantially as drafted.
More Heat on the Horizon?
Just like a California summer, Cal/OSHA’s efforts aren’t cooling down anytime soon. Additional revisions may be made to the August 2026 proposal following the public comment period before Cal/OSHA initiates formal rulemaking under California’s Administrative Procedure Act. Interested stakeholders have until September 21, 2026 to submit comments.
Workplace Solutions
If adopted as-is, the August 2026 proposal would significantly expand employers’ existing heat-related obligations and create additional requirements. But don’t sweat it, the authors, your favorite Seyfarth attorney, or any member of the Workplace Safety and Environment Team are here to advise on the August 2026 draft and any future iterations.
Edited By: Catherine Feldman








