California regulates workplace heat twice. Section 3395 of Title 8 — the outdoor standard — has governed fields, construction sites, and yards for years. Section 3396 brought the same discipline indoors: warehouses, kitchens, laundries, manufacturing floors. The two standards share machinery (water, cool-down access, acclimatization, training, a written plan) but trigger differently, and the employers getting cited in 2026 are mostly the ones who assumed the indoor rule was a copy of the outdoor one.
Everything quoted below is from the regulations as published on the Department of Industrial Relations' own Title 8 pages.
Who is covered, and at what temperature
Outdoors (3395): the standard applies to outdoor places of employment, with specific industries (agriculture, construction, landscaping among them) called out for the high-heat procedures. The shade obligation begins at 80°F: "Shade shall be present when the temperature exceeds 80 degrees Fahrenheit," maintained in one or more areas while employees are present. High-heat procedures kick in at 95°F.
Indoors (3396): the standard "applies to all indoor work areas where the temperature equals or exceeds 82 degrees Fahrenheit when employees are present." A second, hotter tier applies additional provisions where "the temperature equals or exceeds 87 degrees Fahrenheit," where "the heat index equals or exceeds 87 degrees Fahrenheit," or — the one employers miss — at lower temperatures when "employees wear clothing that restricts heat removal" or work in high radiant heat areas at 82°F. There is a narrow exception for brief exposures (82–95°F for under 15 minutes in any hour), which expressly does not cover vehicles without working air conditioning.
If your facility hits 82°F on summer afternoons — most non-climate-controlled warehouses do — you are covered.
The shared core duties
Water. Both standards use the same formula: drinking water "in sufficient quantity at the beginning of the work shift to provide one quart per employee per hour for drinking for the entire shift," with smaller starting quantities allowed only where effective replenishment procedures exist. Fresh, pure, suitably cool, as close as practicable to the work.
Cool-down access. Employees "shall be allowed and encouraged to take a preventative cool-down rest" when they feel the need — in shade outdoors, in a designated cool-down area indoors, which must be blocked from sun and shielded from radiant heat sources, open to the air or ventilated. Access is "permitted at all times," and an employee taking a cool-down rest must be monitored and may not be ordered back to work until symptoms resolve.
Acclimatization. Both standards define acclimatization as the body's gradual adaptation to heat, peaking "within four to fourteen days of regular work." Practically: new employees must be closely observed — the outdoor standard specifies observation by a supervisor or designee "for the first 14 days of the employee's employment" in high-heat conditions, and all employees must be watched during heat waves. The first two weeks of a summer hire's employment is exactly when heat claims cluster; the regulation is written around that fact.
High-heat procedures (outdoor, 95°F). Effective communication "by voice, observation, or electronic means," observation of employees for heat illness, pre-shift meetings "to review the high heat procedures, encourage employees to drink plenty of water, and remind employees of their right to take a cool-down rest" — with additional mandatory rest provisions for agriculture.
A written plan. Both standards require written heat illness prevention procedures. The regulation's own notes say the measures "may be integrated into the employer's written Injury and Illness Prevention Program required by section 3203 … or maintained in a separate document" — meaning your IIPP can carry it, but something written must exist, in English and the language the majority of employees understand.
Training. Both standards require "effective training" for "each supervisory and non-supervisory employee before the employee begins work" that can reasonably be anticipated to involve heat exposure — risk factors, water, cool-down rights, symptoms, emergency response, and the employer's procedures. Supervisors get additional training on their response duties.
What belongs in the handbook
The regulations live in your safety program, but the handbook is where employees learn their rights exist. Three clauses earn their place:
- The cool-down right, stated plainly — employees may take a preventative cool-down rest whenever they feel the need, without discipline. (A policy that's silent here, next to a production-quota policy that isn't, is how retaliation claims get built.)
- Water and reporting — where water is, and who to tell about heat symptoms, immediately, including a co-worker's.
- The acclimatization notice — new and returning employees will be observed during their first two weeks in hot work, and schedule adjustments during heat waves are a safety measure, not a performance signal.
For PEOs, this is a client-site exposure: the standard applies where the work happens, and the written plan, the training records, and the cool-down practice all need to exist at facilities you don't control. Build the plan template and the training log into client onboarding for any client with warehouse, kitchen, or outdoor exposure.
HandbookIQ's California library includes heat illness clauses for both standards, keyed to the trigger temperatures above. Check whether your handbook says any of this.
Quotes are from 8 CCR §§ 3395 and 3396 as published by the DIR. The regulations contain industry-specific provisions (agriculture, for one) beyond this summary — read the full text for your operation.