California’s periodic heat waves began early this year, prompting Cal/OSHA press releases starting in March.  See Releases 2026-24 (“Very Hot Wednesday – Saturday”) and 2026-25 (“Dangerous Heat Wave This Week”). There have been more since, likely to accelerate with Memorial Day approaching.

Heat illnesses range from mild to deadly, with mild to severe heat rash and heat cramps the less extreme reactions.  The two most serious are: heat stroke (e.g., red, hot dry skin, high body temperature, muscle twitching, confusion, fainting, convulsions, unconsciousness); and heat exhaustion (e.g., dizziness, headache, sweaty skin, fast heartbeat, nausea, vomiting, weakness, and/or cramps).

Employers with outdoor workers must have an effective written heat illness prevention plan, following Cal/OSHA’s six protective measures:

• Observe - Closely observe all employees during a heat wave, especially those newly assigned to a high heat area, and provide lighter work, frequent breaks or shorter hours to help acclimate.
• Train - Train all employees and supervisors on heat illness prevention.
• Water - Provide free, cool, fresh, pure drinking water so each worker can drink at least one quart per hour and encourage workers to do so.
• Rest – Encourage all needed cool-down rests in the shade for at least five minutes to avoid overheating.
• Shade - Provide proper shade when temperatures exceed 80 degrees and permit workers to cool off in the shade at any time upon request.

Certain industries have additional high-heat requirements: agriculture, construction, landscaping, oil and gas extraction, and transportation of agricultural products, construction materials or other heavy materials.

Cal/OSHA’s Consultation Services Branch has a help line at 800-963-9424 for workplace health and safety questions.

Take-Aways:

Employers must take heat illness prevention obligations seriously, ensuring they provide such protections to all working in high heat conditions, outdoors and indoors.

For further information, please contact Tim Bowles, Cindy Bamforth or Helena Kobrin.

See also:

• It's Hot Again: Ramp Up Heat Illness Prevention Measures (July 3, 2025)
• In the Hot Seat: Employer Pays Big for Ignoring Extreme Conditions (January 10, 2025)
• Chill Skill: California's New Indoor Heat Rules (August 2, 2024)

Helena Kobrin

May 14, 2026

‍