Heat, cold and outdoor safety in California: alerts, warning signs, cooling centers and your rights

This page is not a live alert or forecast. It cannot tell you what is in effect where you are. For current alerts, go to weather.gov and enter your city or ZIP code, or check CalHeatScore for your California ZIP code.

The short answer

• Check the forecast two ways: the National Weather Service (NWS) alert for your area, and a 0-to-4 heat scale (NWS HeatRisk, or California’s CalHeatScore). Under an Extreme Heat Warning, or at level 3 or 4, move outdoor plans and stay somewhere air-conditioned.
• Call 911 for heat stroke: a body temperature of 103°F or higher, confusion, passing out, or hot, red, dry or damp skin. A body temperature below 95°F (hypothermia) also needs care immediately.
• Fans are not enough in extreme heat. If home is too hot, go to a cooling center or an air-conditioned home.
• Heat safely. Keep space heaters 3 feet from anything that can burn. Run generators only outside, at least 20 feet from the home. Put carbon monoxide (CO) alarms on every level.
• Know your shutoff protections. PG&E, SCE, SDG&E and SoCalGas may not cut off a home for nonpayment when freezing weather is forecast, and in July 2026 regulators voted to lower the heat trigger for electric shutoffs from 100°F to 90°F.
• At work and in the car: California requires free water, shade above 80°F outdoors and a cool-down area below 82°F indoors. Never leave a child 6 or younger, or a pet, alone in a parked car.

Reading the forecast: alerts, HeatRisk and CalHeatScore

NWS alerts tell you when your area faces dangerous weather. HeatRisk and CalHeatScore rate how hard each day’s heat is likely to be on health, several days ahead, so you can plan.

On its Understanding Heat Alerts page, the NWS says an Extreme Heat Watch means be prepared: plan to stop major outdoor activities, and line up a cooling shelter or an air-conditioned place to stay. A Heat Advisory covers dangerous heat below warning level; consider postponing outdoor activities. An Extreme Heat Warning means extremely dangerous heat is expected or happening: avoid outdoor activities and stay in air conditioning as much as possible, including overnight.

The HeatRisk scale

HeatRisk weighs how unusual the heat is for the time of year, how long it lasts through the day and night, and CDC data on when heat starts to harm health. The NWS calls it experimental, says it adds to official alerts rather than replacing them, and gives no guarantee it will always be available. Its HeatRisk fact sheet describes each level:

In California, OEHHA’s CalHeatScore ranks heat by ZIP code. Level 2 (“moderate”) is a very warm day with more health effects for heat-sensitive people; level 3 (“high”) brings more effects for everyone, especially people without cooling or doing hard outdoor work; level 4 (“severe”) is an extreme heat day. If an alert and a scale disagree, follow the more protective advice.

Cold alerts follow the same pattern: a watch means get ready, a warning means act. For current cold and freeze alert names, see our guide to weather watches, warnings and advisories.

Heat illness: the warning signs and when to call 911

The NWS Phoenix office describes heat illness as a progression: thirst, then heat cramps, then heat exhaustion, then heat stroke. The CDC’s quick guide sets out what to look for and what to do:

The CDC’s workplace safety institute, NIOSH, adds two conditions that matter for people who work or train hard in the heat. Rhabdomyolysis (muscle breakdown) causes muscle pain or cramps, dark tea- or cola-colored urine and weakness; stop, drink fluids and get immediate care at the nearest medical facility. Heat syncope is brief fainting or dizziness, often after standing a long time; sit or lie down somewhere cool and slowly drink water.

For more on heat illness, read Heat-Related Illness: Protecting Yourself in the Central Valley.

Cold: hypothermia and frostbite

Hypothermia is a dangerous drop in body temperature. The CDC lists shivering, exhaustion, confusion, fumbling hands, memory loss, slurred speech and drowsiness in adults, and bright red, cold skin and very low energy in babies. It can happen above 40°F if a person is chilled by rain, sweat or cold water. What to do, from the CDC’s Preventing Hypothermia page:

1. Take the person’s temperature. If it is below 95°F, get medical attention immediately.
2. If help is not immediately available, move them somewhere warm and take off wet clothing.
3. Warm the center of the body first (chest, neck, head and groin) with an electric blanket, or skin-to-skin under loose, dry layers.
4. Warm drinks can help a person who is awake. Never give alcohol, and never give a drink to someone who is unconscious.
5. Once they warm up, keep them dry and wrapped in a blanket, including the head and neck.

Frostbite is frozen skin and the tissue under it. The CDC’s Preventing Frostbite page says redness or pain may come first, then skin that is white or grayish-yellow, unusually firm or waxy, or numb. Get into a warm room and check for hypothermia first. Do not walk on frostbitten feet unless you must, and do not rub the area or rub it with snow. Warm it in water that feels comfortable on unaffected skin, or with body heat. Do not use a heating pad, heat lamp, stove or fireplace, because numb skin burns easily. Have any frostbite checked by a health care provider.

Who is most at risk

• Heat. The CDC names older adults, young children and people with chronic medical conditions as at high risk of heat-related illness and death. The NWS adds people without effective cooling or enough fluids, visitors not used to the heat, and anyone outdoors or active in the sun for long periods. New workers are at risk too.
• Medicines. Some common medicines, including water pills, several blood pressure and heart medicines, lithium and some psychiatric medicines, make heat harder to handle. Do not stop any medicine on your own. Read medicines that can raise your risk in a heat wave, then ask your clinician or pharmacist for a hot-day plan.
• Cold. The CDC lists older adults without enough food, clothing or heat; babies sleeping in cold bedrooms; people outdoors for long periods, including people experiencing homelessness, hikers and hunters; and people who drink alcohol or use drugs. Poor circulation raises frostbite risk.

If someone you know is in one of these groups, agree on a daily check-in during heat and cold alerts. The NWS Phoenix office notes that children “need much more frequent watching” in the heat.

Cooling and warming centers: how to find one

Counties and cities open cooling centers during heat waves and warming centers in cold snaps. Locations and hours change from one event to the next.

1. Check CalHeatScore. OEHHA says the tool shows the nearest cooling center locations for your ZIP code.
2. Check your county. Cal OES, the Governor’s Office of Emergency Services, has pointed residents to county cooling-center listings during heat waves. Counties also post warming centers; Tulare County, for example, may open extra 24-hour centers during “extreme cold emergencies.”
3. Call before you go. Tulare County advises asking about hours and services; its centers offer at least heat, seating and restrooms.
4. Pack for several hours: medicines and a written medicine list, water, a phone charger, and what a child or a person you care for needs. Ask ahead about pets.
5. Have a backup. The NWS suggests staying with people who have air conditioning. For warmth, Tulare County suggests stores, malls, movie theaters, or a relative’s or friend’s home.

If a disability or lack of transport would keep you from a center, ask your county emergency services office about help before the season starts.

Keeping your home cool safely

Air conditioning is the most reliable protection. The CDC says to stay in an air-conditioned indoor location as much as you can. Fans and open windows help less as the heat gets worse.

Wear loose, light-colored clothing and drink water before you feel thirsty. If a clinician has limited how much you drink, ask them what to do in a heat wave rather than changing the limit yourself.

If a high bill is making you skip air conditioning, see lowering your utility bills in California for discounts and payment plans. If anyone at home uses powered medical equipment or medicine that must stay cold, see a power outage plan for a household that uses medical equipment.

Keeping warm safely: space heaters, carbon monoxide and generators

The U.S. Consumer Product Safety Commission (CPSC) reports that portable heaters are involved in an average of 1,600 fires a year, causing about 70 deaths and 160 injuries a year (2019 to 2021). It also counts about 750 deaths from carbon monoxide (CO) poisoning linked to generators from 2012 to 2022. CPSC’s advice:

• Keep space heaters at least 3 feet from anything that can burn.
• Plug electric space heaters directly into a wall outlet, never into an extension cord or power strip.
• Never leave a portable heater on while you sleep.
• Have a professional inspect your furnace and other fuel-burning heating every year, and have your chimney checked for cracks, blockages and creosote.
• Run a portable generator outside only, at least 20 feet from the home, with the exhaust pointed away from buildings. Never run it in a home, basement, shed or garage.
• Put CO alarms on every level and outside sleeping areas. Use battery-operated or battery-backup alarms, and test them monthly.

Utility bills and shutoff protections in extreme weather

The California Public Utilities Commission (CPUC) sets disconnection rules for Pacific Gas and Electric (PG&E), Southern California Edison (SCE), San Diego Gas & Electric (SDG&E) and Southern California Gas (SoCalGas). These rules cover shutoffs for unpaid bills, not outages from storms, equipment failures or wildfire-safety shutoffs.

About the new heat rule. The CPUC’s revised draft of Resolution E-5468 was set for a vote on July 16, 2026. It keeps the 72-hour look-ahead and leaves SoCalGas under the 32°F cold rule only. The consumer group TURN reported that day that the commission agreed to the 90°F trigger, and NBC Palm Springs reported a unanimous vote. We could not open the final signed resolution, so ask your utility which heat threshold it is using. The other protections in the table come from the CPUC’s 2024 report on disconnections.

If you get a shutoff notice in hot or cold weather:

1. Call the number on your printed bill, not one from a text or voicemail. Ask for a payment plan, and ask whether a temperature protection applies in the next three days.
2. Tell the utility if anyone at home relies on powered medical equipment or has a serious illness, and ask about Medical Baseline.
3. Apply for bill help. Our guide to lowering your utility bills in California explains CARE, FERA and LIHEAP and how to complain to the CPUC. Keep notes on every call.

If a city-owned utility or an irrigation district serves you, ask it about its own rules for extreme weather.

Planning outdoor activity around heat and cold

• Go early. The NWS Phoenix office says the coolest time is usually 4 to 7 a.m. Cal OES advises avoiding strenuous activity and direct sun from noon to 6 p.m.
• Let the forecast set the plan. At HeatRisk level 2, shift activity to cooler times; at level 3, consider canceling activity in the hottest hours; at level 4, strongly consider canceling outdoor plans.
• Take breaks in shade or air conditioning, pace yourself, and wear sunscreen; Cal OES recommends SPF 30 or higher.
• Watch the people who may not speak up: children, older adults and anyone new to the heat. Give pets plenty of cool, fresh water.
• In cold weather, plan for getting wet. Hypothermia can set in above 40°F if you are chilled by rain, sweat or cold water, so pack dry layers for hikes, fishing trips and hunts.

Stop and cool down at the first sign of heat illness, and warm up at the first sign of hard shivering, numbness or confusion. Do not push on to finish a game, a hike or a shift.

Children, pets and parked cars: what California law says

Cal OES warns that the temperature inside a car “can reach 100 degrees in less than 10 minutes,” and the CDC says never to leave children or pets in cars.

An animal in danger in a locked car. Section 597.7 protects a rescuer from criminal liability only if they act reasonably and in good faith: the car is locked with no other way to get the animal out; they believe forcing entry is needed to prevent imminent harm; they contact law enforcement, the fire department, animal control or 911 first; they use no more force than needed; and they stay with the animal nearby until a responder arrives, then hand it over.

If you see a child alone in a hot car, call 911 at once. Check the back seat every time you lock up.

At work: California’s outdoor and indoor heat standards

California has two enforceable workplace heat rules, both enforced by Cal/OSHA. The indoor rule was approved by the Occupational Safety and Health Standards Board on June 20, 2024, and took effect July 23, 2024. This summary comes from Cal/OSHA’s heat illness guidance and its outdoor heat page.

Water. Outdoors, water must be fresh, suitably cool, free and close to the work. Cal/OSHA says to provide enough for each worker to drink at least 1 quart an hour, and to encourage drinking.

New workers and emergencies. Under the outdoor rule, employers must closely observe new and newly assigned workers in hot areas for 14 days, and all workers during a heat wave. Employers must respond to signs of heat illness, including by contacting emergency medical services.

Federal rules. Federal OSHA proposed a national heat standard on August 30, 2024, held hearings in June and July 2025, and took final post-hearing comments until October 30, 2025. Its rulemaking page lists no final rule as of 29 October 2026. California’s standards apply now.

The Cal/OSHA guidance we read is dated August 2024 and lists no later changes; check the current text of sections 3395 and 3396 before relying on a specific trigger in a dispute. For the indoor rule’s water and rest duties, and how both rules apply in fields, packing houses and warehouses, see California’s two workplace heat standards.

Your rights to water, shade and rest

These are legal duties on your employer, not favors: free, cool water close to where you work; shade outdoors above 80°F; heat illness training; and emergency help if you get sick. Cal/OSHA says employers must let workers who ask for a cool-down rest take one and watch them for symptoms. Its advice to workers: do not wait until you feel sick to cool down.

If the water, shade or rest is missing:

1. Tell your supervisor or safety representative, and write down the date, time and who you told.
2. File a workplace safety complaint with Cal/OSHA; its heat illness page links to the form.
3. If you are punished for speaking up, contact the Labor Commissioner’s Office, which handles retaliation.
4. If you became ill at work, ask the Division of Workers’ Compensation about benefits.

If a coworker shows signs of heat stroke, call 911 first, start cooling them, then tell a supervisor.

Before the season: a household checklist

• Bookmark weather.gov and CalHeatScore for your ZIP code.
• Pick two cool places and two warm places you can reach, and how you will get there.
• Ask your clinician or pharmacist whether your medicines raise heat risk.
• Service your air conditioner and furnace early. Test CO alarms monthly.
• If anyone uses powered medical equipment, tell your utility and write an outage plan.
• Apply for bill discounts now, not in the middle of a heat wave.
• Set up daily check-ins with an older neighbor or relative for heat and cold alerts.

Also on this site: Medicines that can raise your risk in a heat wave, Heat-Related Illness: Protecting Yourself in the Central Valley, California’s two workplace heat standards, A power outage plan for a household that uses medical equipment, Weather watch, warning or advisory and Lowering your utility bills in California each go deeper on one part of this guide.

Where to get free help

• 911 for heat stroke, severe hypothermia, a CO alarm, or a child or animal in danger in a car.
• National Weather Service (weather.gov): alerts and HeatRisk for your area.
• California Office of Environmental Health Hazard Assessment: CalHeatScore by ZIP code, with nearby cooling centers.
• Your county office of emergency services: cooling and warming centers and local alerts.
• California Public Utilities Commission: complaints about PG&E, SCE, SDG&E or SoCalGas, including disconnections.
• Cal/OSHA (Department of Industrial Relations): workplace heat complaints and guidance.
• Labor Commissioner’s Office: retaliation for raising a safety concern.
• Local animal control or police: animals in danger in parked cars.
• Your clinician or pharmacist: a personal plan for heat and cold.

Sources

1. Understanding Heat Alerts — National Weather Service, accessed October 29, 2026.
2. NWS HeatRisk (experimental) fact sheet — National Weather Service, 2024.
3. Understanding HeatRisk — National Weather Service fact sheet (Albany, NY office), accessed October 29, 2026.
4. Heat — National Weather Service, Phoenix, AZ office, accessed October 29, 2026.
5. Heat-Related Illnesses: What to look for, what to do — Centers for Disease Control and Prevention, accessed October 29, 2026.
6. Heat-related Illnesses — CDC, National Institute for Occupational Safety and Health, last reviewed March 3, 2026.
7. Protect Yourself From the Dangers of Extreme Heat — CDC, last reviewed June 25, 2024.
8. Preventing Hypothermia and Preventing Frostbite — CDC, last reviewed August 25, 2026.
9. State Launches a New Feature to CalHeatScore to Make Extreme Heat Info Accessible to More Californians — California Office of Environmental Health Hazard Assessment, May 21, 2026.
10. Staying Safe During Extreme Heat — California Governor’s Office of Emergency Services, July 11, 2023.
11. Warming Centers — County of Tulare, accessed October 29, 2026.
12. There’s a Chill in the Air: Stay Warm Safely; Be Cautious When Using Generators, Furnaces and Space Heaters — U.S. Consumer Product Safety Commission, January 22, 2025.
13. Draft Resolution E-5468, Agenda Item 18 (Rev. 1), R.18-07-005 — California Public Utilities Commission, Energy Division, agenda date July 16, 2026.
14. California Strengthens Protections Against Disconnections During Extreme Heat — The Utility Reform Network (TURN), July 16, 2026; and California lowers heat threshold for utility shutoff protections — NBC Palm Springs, July 23, 2026.
15. Report to the Legislature on Residential and Household Utility Service Disconnections (Public Utilities Code section 910) — California Public Utilities Commission, April 2024.
16. Cal/OSHA Heat Illness Prevention Guidance and Resources — California Department of Industrial Relations, August 2024 (accessed October 29, 2026); and Outdoor Heat Illness Prevention — California Department of Industrial Relations, June 2024.
17. California Vehicle Code section 15620 — Justia (2025 California Code), accessed October 29, 2026.
18. California Penal Code section 597.7 — FindLaw, current as of January 1, 2026, accessed October 29, 2026.
19. Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings Rulemaking — U.S. Occupational Safety and Health Administration, accessed October 29, 2026; and Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings: extension of post-hearing comment period — Federal Register, September 25, 2025.