Water, shade, and a room below 82°F: what California’s two heat standards actually require
California runs an outdoor heat standard and an indoor one. They have different triggers, different duties and different second tiers — and in a valley whose fastest-growing employers are metal-roofed buildings beside Highway 99, the indoor rule is frequently the one that binds first.
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California is one of a small number of states with an enforceable workplace heat standard, and the only one running two of them at once. Federal OSHA proposed a national heat rule in August 2024 and has not finalised it; California employers have had binding duties for far longer, and since those duties reach indoors as well. In a county where triple-digit afternoons are ordinary rather than exceptional, the distinction between the two standards decides what your employer owes you today.
October 10, 2026 edition · Developments from September 25 to October 10
Latest record
Dated alert with continuing guidance · Source published · Event
The weather advisory was time-limited; prevention duties continue.
Cal/OSHA’s October 2 reminder called attention to heat risks in several California regions, including the San Joaquin Valley. Those dated forecasts should not appear as an active October 10 weather alert without a new forecast check.
The agency’s guidance addresses indoor and outdoor workplace protections, including access to water, rest or cooling arrangements and training. Workplaces may be covered by both sets of rules. Employers and workers should use the current Cal/OSHA guidance and current local weather rather than infer that heat risk ends with the summer calendar.
Section 3395 of Title 8 of the California Code of Regulations covers outdoor places of employment. Section 3396, approved by the Occupational Safety and Health Standards Board on and effective from , covers indoor places of employment. An employer with both — a packing house with a yard, a workshop with a delivery bay — is covered by both, evaluated area by area rather than site-wide.
Outdoor section 3395 compared with indoor section 3396
Duty
Outdoor — § 3395
Indoor — § 3396
When it applies
All outdoor places of employment.
Indoor workplaces once the temperature reaches 82°F.
Drinking water
Potable, fresh, suitably cool, free of charge, and located as close as practicable to where people are working.
Somewhere to cool down
Shade must be present above 80°F, and available on request below it.
At least one cool-down area maintained below 82°F.
Second tier
High-heat procedures at 95°F in agriculture, construction, landscaping, oil and gas extraction, and transportation of agricultural or construction materials.
Additional control measures at 87°F — or at 82°F where clothing restricts heat removal or there is high radiant heat.
Written plan
A heat illness prevention plan, implemented and followed.
An indoor heat illness prevention plan, plus temperature and heat-index assessment records.
Training, acclimatisation, emergency response
Required under both, for employees and supervisors.
What this means where the work actually is
The Valley’s employment profile puts an unusually large share of its workforce in the second tier of both standards rather than the first. Agriculture and construction are named industries for the 95°F outdoor high-heat rule — which adds observation requirements, mandated communication, and a supervisor duty that is not discretionary. Warehousing, packing, food processing and distribution — the sectors that have grown fastest along the Highway 99 corridor — are the paradigm case for the indoor standard, because a metal-roofed building with restricted airflow passes 82°F long before the outside air does.
That produces the counterintuitive result worth carrying away: on a 96°F Fresno afternoon, the person with the clearer set of written entitlements is often the one indoors, not the one in the field — because the indoor standard triggers on measured temperature in the room, and a room can be hotter than the forecast.
Acclimatisation, and the two days that carry most of the risk
The requirement that is most often absent in practice is acclimatisation: close observation of an employee during a heat wave, and of any new employee for their first fourteen days. This is not an administrative detail. Heat illness is disproportionately concentrated in the earliest days of a new assignment and in the first days of the first serious heat event of a season, because physiological adaptation has not occurred and because a new worker is least likely to stop.
A written plan that does not name who performs that observation, and when, is a plan that will not survive a Cal/OSHA inspection — and, more to the point, will not prevent the thing it exists to prevent.
If the water, the shade or the room is not there
Three routes exist and they are not equivalent. The first is internal — a supervisor or safety representative, which resolves most problems and creates no record. The second is a Cal/OSHA complaint, which may be made confidentially; the identity of a complainant is not disclosed to the employer, and Cal/OSHA may inspect on the basis of it. The third, where there is imminent danger, is an immediate report rather than a written complaint.
Retaliation for raising a safety concern or filing a complaint is separately unlawful under Labor Code section 6310 and is handled by the Labor Commissioner rather than by Cal/OSHA. Both can be pursued; they are different offices with different remedies, and confusing them is the commonest way a valid claim goes to the wrong desk.
How to verify this yourself
Primary sources on California heat illness prevention
Question
Where the answer is published
The two standards in full, and the comparison table Cal/OSHA publishes
This page reports what public documents say. It is not legal, financial, insurance or tax advice, and no professional relationship arises from reading it. Where it draws a conclusion, the conclusion is labelled and the counterargument is stated.
Everyday · revised 18 September 2026, 3:00 PM PT.
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