Extreme Heat and Health: Recommendations and Resources for Local Health Jurisdictions (LHJs) and Local Responders / Service Providers
As climate change is making our summers hotter, California is entering the hottest and longest heat wave this year. It's important to stay informed and protect those most vulnerable from hot temperatures by providing guidance on how to stay cool at home or in place, finding other locations to stay cool, and being able to access resources and services to help stay safe in the heat.
Heat-related illnesses include cramps, heat exhaustion and most seriously, heat stroke and death. Warning signs of heat-related illnesses vary, but may include heavy sweating, muscle cramps, weakness, headache, nausea or vomiting, paleness, tiredness or dizziness.
To learn more about the warning signs and symptoms of heat-related illnesses, visit the CDC's page on heat-related illness.
What to Do
Public health is centered on preventing negative health outcomes from occurring in the first place. But if you or someone you know is suffering from heat-related illness, below are steps for what to do (Source: CDC; Spanish version):
Call 9-1-1 right away – heat stroke is a medical emergency
Move the person to a cooler place
Help lower the person's temperature with cool cloths or a cool bath
Do not give the person anything to drink
Move to a cool place
Put cool, wet cloths on body or take a cool bath
Get medical help right away if: someone throwing up; symptoms get worse; or symptoms last longer than 1 hour
Stop physical activity and move to a cool place
Drink water or a sports drink
Wait for cramps to go away before you do any more physical activity
Get medical help right away if: cramps last longer than 1 hour; someone is on a low-sodium diet; or someone has heart problems
Preventing Heat-Related Illness:
Share information with your communities about how to stay safe, including sharing resources in the CDPH heat safety communications toolkit, extreme heat webpage, and tips posted on the CDPH social media accounts.
Below are additional resources and guidance recommendations for protecting your communities during extreme heat events.
Keeping Populations with Greater Vulnerability Safe
Priority populations include (but are not limited to):
People without electricity (if power goes out due to demand or other reason) - particularly those dependent on medical equipment, refrigeration (of medicines, etc.), living in under-resourced communities, etc.
Those living in single room occupancy (SRO) hotels
Those living in geographic areas where homes historically have not needed, and do not have, air conditioning (i.e., coastal communities)
People with access and functional needs
People who are socially and/or linguistically isolated
People with substance use disorder and/or mental illness
Infants and very young children
Elderly and aging population
For additional guidance and tips for ways to stay safe during an extreme heat wave, please see the CDPH Extreme Heat information page.
If air conditioning is not available in someone's home:
Provide information on how to stay cool at home:
Use a fan to stay cool.
Ceiling fans: setting fan to rotate counterclockwise will push air down. Check to see if your ceiling fan can do this.
REMINDER: While electric fans might provide some comfort, when temperatures are really hot, they won't prevent heat-related illness.
Keep blinds and drapes closed.
Freeze wet paper towels to put on your neck. Use other frozen items (e.g., bags of frozen veggies, etc.)
Take a cold shower or bath.
Close doors in unused rooms to keep cold air where you need it.
Turn on bathroom and stove top fans to suck hot air out.
Avoid using your stove and oven to maintain a cooler temperature in your home.
If someone is unhoused, or living somewhere that does not provide adequate cooling or does not have power:
For Those Who Can Travel To Another Location:
- Other public places with air conditioning:
If you have a pet or a companion animal:
Pets and companion animals feel the heat just as much as humans do and they can also suffer from heat-related illnesses. Know the symptoms of overheating for animals, including excessive panting or difficulty breathing, increased heart and respiratory rate, drooling, mild weakness or lethargy, stupor or even collapse, excessive thirst, and vomiting. Help protect the health of pets and other companion animals during an extreme heat event by taking these steps.
Never leave pets in a parked vehicle. Even cracked windows won't protect your pet from suffering from heat stroke, or worse, during hot summer days.
Provide your pet with fresh, cool water every day in a tip-proof bowl.
Don't force animals to exercise when it is hot and humid. Exercise pets early in the morning or late in the evening when temperatures are cooler.
Bring pets inside during periods of extreme heat.
Ensure pets have plenty of shade and shelter if kept outside. Remember, the shade pets have in the morning will either change or diminish as the sun moves throughout the day and may not protect them.
Asphalt and concrete can get very hot and cause severe burns on the pads of your pet's feet.
Older and overweight pets are more likely to overheat during hot weather.
Animals with flat faces are more susceptible to heat stroke since they cannot pant as effectively. These pets, along with older and overweight pets, should be kept in an air-conditioned environment as much as possible.
Keep your pet well-groomed, but resist the temptation to shave off all of their hair to keep them cool. A pet's coat will protect it from getting sunburned and acts as a cooling insulation for most animals.
It is important to work with your local cooling centers to allow pets and other companion animals inside, since many people may not want to or are not able to leave their pets behind.
Protecting farm animals:
Protecting Students Engaging in Outdoor Sports and Strenuous Activities
CDPH Interim Health Guidance for Schools on Sports and Strenuous Outdoor Activities during Extreme Heat (released September 6, 2022):
- The CDPH interim health guidance provides additional or supplemental information and guidance; if a school or local jurisdiction has an existing heat emergency plan, consult with the existing plan first.
Know your location's "HeatRisk" level. Cancel all outdoor and un-conditioned indoor activities when the HeatRisk level is Red or Magenta during the heat of the day. Find your HeatRisk level here: NWS HeatRisk forecast (for details, see the HeatRisk grid). If in doubt, cancel.
Reschedule events to another day when the HeatRisk level is no longer Red or Magenta, or to another time of day, when the temperature is one to which the students have acclimated, for example, very early morning.
Move to alternative activities in an air-conditioned or cooled indoor environment if the HeatRisk level is forecasted to be Red or Magenta.
Multiple days of extreme high temperatures will make students and athletes more vulnerable to exertional heat-related illness, even at lower temperatures.
Always monitor for exertional heat-related illness because there are multiple contributing factors of which temperature is just one. Humidity, wind speed, and sun angle are other environmental contributors to the risk of heat-related illness.
Review CDPH Interim Health Guidance for Schools on Sports and Strenuous Outdoor Activities during Extreme Heat. If a circumstance is unclear/uncertain, cancel or reschedule the event, or move the event to alternative activities in a cooled indoor environment.
Protecting Workers from Extreme Heat
California employers are required to take these four steps to prevent heat illness:
Training: Train all employees and supervisors about heat illness prevention.
Water: Provide enough fresh water so that each employee can drink at least 1 quart per hour, or four 8-ounce glasses, of water per hour, and encourage them to do so.
Shade: Provide access to shade and encourage employees to take a cool-down rest in the shade for at least 5 minutes. They should not wait until they feel sick to cool down.
Planning: Develop and implement written procedures for complying with the Cal/OSHA Heat Illness Prevention Standard.
Local Examples: Extreme Heat Response Measures
Sending out information through mutiple communication channels such as:
Through the Sheriff's Program site:
"Elder Orphans is a telephonic messaging service which stores subscriber's name, telephone number, address, emergency contact information, and call times. The program was created by the Madera County Sheriff's Office to meet the needs of Madera County's Senior Citizens who live alone. Elder Orphans is a free house check calling program for people who want daily contact by receiving a pre-recorded message on their home phone. You select when you want us to call you and how often."
Local protocol: Maintain open lines of communication with our utility providers to know whether they expect disruption to their systems. In this case, local utility, PG&E, is very good at communicating with their customers directly if there are any concerns. Trinity County distributes messaging via social media about staying cool and limiting outdoor activity during excessive heat. Currently, due to the fires, Trinity County also has 'clean air centers' that can double as a cooling center for the public and these are also advertised to the community.
Yuba / Sutter Counties:
Ensure that pets are allowed at the cooling centers (indoors - not just kenneled outside)
Transportation is very important so ensure that local transit is open (especially during holidays and weekends)
Outreach to Access and Functional Needs clients and IHSS clients is important to ensure they have all the information and assistance that they need
Consider having specific cooling options for unhoused clients separate from general population
San Francisco City / County:
Developed Extreme Heat public health response guidance document for the Department
Provides information on extreme heat emergencies, heat-related health conditions, vulnerable populations, temperature thresholds, activation and notification phases, potential city-wide impacts, lead response and partner agencies, and more.
Key Consideration for Vulnerable Populations: Guidance for San Francisco population (and other populations and geographic locations) that have historically not experienced extreme heat events for extended durations:
"the population – in particular…vulnerable groups… -- has greater difficulty acclimating to long durations of extremely high temperatures. This causes an increased risk of heat stress and of heat related illness, which could subsequently result in death. Furthermore, the housing stock in San Francisco is also less likely to have central air conditioning both because of its age and because of the typically cooler climate."
Los Angeles County
Ready LA County – Extreme Heat site published
Comprehensive / centralized website for providing locations of cooling centers, guidance on staying safe during extreme heat, and more
The OSHA-NIOSH Heat Safety Tool is a useful resource for planning outdoor work activities based on how hot it feels throughout the day. It has a real-time heat index and hourly forecasts specific to your location. It also provides occupational safety and health recommendations from OSHA and NIOSH.
The OSHA-NIOSH Heat Safety Tool features:
A visual indicator of the current heat index and associated risk levels specific to your current geographical location
Precautionary recommendations specific to heat index-associated risk levels
An interactive, hourly forecast of heat index values, risk levels, and recommendations for planning outdoor work activities
Location, temperature, and humidity controls, which you can edit to calculate for different conditions
Signs and symptoms and first aid for heat-related illnesses
Key considerations for using the app (from CDC webpage):
Heat index (HI) values were created for shady, light wind conditions, so exposure to full sunshine can increase heat index values by up to 15°F.
The simplicity of the HI makes it a good option for many outdoor work environments (if no additional radiant heat sources are present, such as, fires or hot machinery). However, if you have the ability, NIOSH recommends using wet bulb globe temperature (WBGT)-based Recommended Exposure Limits (RELs) and Recommended Alert Limits (RALs) in hot environments.
Use of the HI or WBGT is important, but other factors such as strenuous physical activity also cause heat stress among workers. Employers should have a robust heat stress prevention program that ensures workers are protected.
NIOSH and the Occupational Safety and Health Administration (OSHA) are considering new scientific data related to the HI levels, and considering how to best incorporate the evolving science. It is important to regularly download updates to ensure you are using the latest version of the app
Working Together to Keep the Power On: Conserve Energy
To minimize discomfort, help with grid stability, and ensure the power stays for helping communities stay cool, consumers are encouraged to conserve energy. The power grid is usually most stressed from higher demand and less solar energy between 4 p.m. and 9 p.m. During this time, consumers are urged to conserve power by:
Setting thermostats to 78 degrees or higher, if health permits
Avoiding use of major appliances and turning off unnecessary lights
Avoid charging electric vehicles while the Flex Alert is in effect
Consumers are also encouraged to pre-cool their homes and use major appliances and charge electric vehicles and electronic devices before 4 p.m., when conservation begins to become most critical.
Consumers can sign up for Flex Alerts and participate in conserving energy when Flex Alerts are issued. A Flex Alert is typically issued in the summer when extremely hot weather drives up electricity use, making the available power supply scarce. Reducing energy use during a Flex Alert can help stabilize the power grid during tight supply conditions and prevent further emergency measures, including rotating power outages.
Identifying and Prioritizing Communities with Greater Climate Change and Health Vulnerability
Utilize the CDPH Climate Change and Health Vulnerability Indicators (CCHVIs) for California and data visualization platform (CCHVIz) to help define the scope of climate impacts and identify the populations and locations that are most vulnerable to those impacts, including for extreme heat.
The indicators are grouped into three types: 1) Environmental or Climate Exposure Indicators, including for heat, air quality, drought, wildfires, and sea level rise. 2) Indicators that speak to a community's capacity to adapt to climate exposures, including things like air conditioning ownership, tree canopy, impervious surfaces, and public transit access. And lastly, indicators that account for populations with greater sensitivity to climate exposures – including children and elderly, those living in poverty, and data on race and ethnicity, linguistic isolation, disability, and more. The data can be downloaded from our website, along with a description of why each indicator is relevant to climate change and health equity.
Access the tool on CDPH's Climate Change and Health Equity page.