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ADVISORY
Release Number: 2026-72
Date: September 9, 2026

September Heat Alert: Cal/OSHA reminds employers to protect workers from high heat with temperatures expected to reach triple digits across much of the state

With high temperatures expected across multiple parts of California this week, Cal/OSHA is reminding employers to protect workers from heat illness at indoor and outdoor worksites. Employers must take steps to protect workers, including providing access to water, shade or cool-down areas, along with rest breaks and training.

Heat advisories and extreme heat warnings are in effect across Southern California, the Central Valley, and parts of Northern California.

Forecast conditions include:

  • Los Angeles County: Coastal and inland area, including the Malibu Coast, Palos Verdes Hills, downtown Los Angeles, the Santa Monica Mountains, Calabasas, Agoura Hills and the San Gabriel Valley, are under a heat advisory until 8 a.m. Wednesday, followed by an extreme heat warning through 8 p.m. Thursday. Temperatures are expected to reach 92 to 108 degrees Fahrenheit.

    San Diego Weather Map

  • San Bernardino and Riverside counties: An extreme heat warning followed by a heat advisory is in effect for valley communities, including Ontario, Riverside, Rancho Cucamonga, Corona, Moreno Valley, Fontana and San Bernardino. Temperatures are expected to reach 90 to 107 degrees during the warning and the mid-90s to 102 degrees during the advisory. Major heat risk conditions are forecast through Wednesday.
  • Imperial Valley: An extreme heat warning with major heat risk is in effect for Imperial Valley through 8 p.m. Friday, with temperatures expected to reach 106 to 114 degrees.
  • Sacramento and San Joaquin Valleys: A heat advisory is in effect from 10 a.m. Wednesday through 10 p.m. Thursday for the Sacramento, the Delta and the foothills and the San Joaquin Valley and Sierra Foothills, including Sacramento, Stockton, Modesto, Fresno and Bakersfield, with temperatures forecast to reach 97 to 104 degrees.

    Sacramento Weather Map
    Sacramento Weather Map 2

  • Bay Area and Central Coast: A heat advisory is in effect through 10 p.m. Thursday for areas including San Francisco, Napa, Livermore and Big Sur. Inland temperatures are expected to range from the 90s to 105 degrees.

    SF Bay Area Weather Map

Because weather forecasts are subject to change, employers must remain vigilant, monitor local forecasts and ensure required heat protections remain in place. Visit the National Weather Service website for the latest forecasts and specific areas under heat alerts.

Heat illness is a serious and potentially fatal workplace hazard. Under Cal/OSHA’s Heat Illness Prevention Standards, employers are legally required to protect workers from heat-related illness in both indoor and outdoor workplaces. Employers may be covered by both the indoor and outdoor regulations if they have workers in each setting. See the Comparison Chart of Indoor and Outdoor Heat Illness Prevention Standards for more information.

Cal/OSHA’s Heat Illness Prevention in Indoor Places of Employment regulation applies to most indoor workplaces, such as restaurants, warehouses and manufacturing facilities. When the temperature in an indoor workplace reaches 82 degrees, employers must take steps to protect workers from heat illness. Some of the requirements include providing water, rest, cool-down areas and training.

To prevent heat illness at outdoor worksites, the law requires employers to provide outdoor workers fresh water, access to shade (which must be in place when temperatures exceed 80 degrees) and, whenever requested by a worker, cool-down rest breaks in addition to regular breaks. In certain industries, when the temperature at outdoor worksites reaches or exceeds 95 degrees, Cal/OSHA’s standard requires additional protections. The industries with additional high-heat requirements are agriculture, construction, landscaping, oil and gas extraction and transportation of agricultural products, construction materials or other heavy materials. High-heat procedures include ensuring employees are observed regularly for signs of heat illness and establishing effective communication methods.

Employers in both settings must also maintain a written prevention plan and provide effective training so supervisors and employees can recognize the common signs and symptoms of heat illness and know what to do in an emergency.

Additional Resources

Cal/OSHA’s Heat Illness Prevention special emphasis program includes enforcement of the heat standards as well as multilingual outreach and training programs for California’s employers and workers. Details on heat illness prevention requirements, training materials and tools are available on Cal/OSHA’s Heat Illness Prevention web page and at 99calor.org.

Cal/OSHA has established the Heat Illness Prevention (HIP) Network, a voluntary partnership aimed at increasing awareness among employers and workers about the importance of preventing heat illness. To join the HIP Network, email HIPNetwork@dir.ca.gov.

About Cal/OSHA

Cal/OSHA helps protect workers from health and safety hazards on the job in almost every workplace in California.

Workers who have questions about safety and health in the workplace can call 833-579-0927 to speak with a live bilingual Cal/OSHA representative between the hours of 9:00 a.m. and 7:00 p.m. Monday through Friday. Complaints about workplace safety and health hazards can be filed confidentially with Cal/OSHA district offices.

Workers in California are protected regardless of immigration status.

Employers who have questions or need assistance with workplace health and safety programs can call Cal/OSHA’s Consultation Services Branch at 800-963-9424.

Cal/OSHA is a division of the California Department of Industrial Relations.

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