County of Marin Health and Human Services

Extreme Heat Events

Prevent Heat-Related Emergencies

Visit the Public Emergency Portal of Marin County to stay up-to-date during excessive heat events.


Mát Mẻ và An Toàn


Visit and be disaster ready..

Encuentra recursos adicionales para prepararte a afrontar el calor.  Visite

Extreme Heat and Public Health

Extreme heat events are prolonged periods of unusually high temperatures that exceed the normal or average climate conditions. Experts project that as our climate changes, extreme heat events will become more frequent, longer lasting, and more severe. The State of California has experienced a rise in temperatures over the past several decades. The increasing temperatures can have significant effects on health of our community members in several ways:

  1. Heat-related Illnesses: As temperatures rise, the risk of heat-related illnesses, such as heat exhaustion and heatstroke, increases. Prolonged exposure to high temperatures can overwhelm the body's ability to cool down, leading to dehydration, heat cramps, heat exhaustion, and potentially life-threatening heatstroke.
  2. Cardiovascular and Respiratory Issues: Heat can exacerbate existing cardiovascular and respiratory conditions. High temperatures and heat waves can place stress on the cardiovascular system, leading to increased heart rate, blood pressure, and the risk of heart attacks and strokes. Heat can also worsen respiratory conditions, such as asthma, as it can trigger breathing difficulties and respiratory distress.
  3. Air Quality: Rising temperatures can worsen air quality in California. Heat can accelerate the formation of pollutants that can irritate the respiratory system and exacerbate respiratory conditions. Increased heat can also contribute to the intensity and frequency of wildfires, releasing smoke and harmful pollutants into the air.
  4. Infectious Diseases: Climate change and rising temperatures can affect the distribution and prevalence of infectious diseases. Warmer temperatures can expand the geographic range of disease-carrying vectors like mosquitoes and ticks, increasing the risk of vector-borne diseases. 
  5. Mental Health Impacts: Extreme heat and prolonged exposure to high temperatures can have mental health implications. Heatwaves can cause discomfort, sleep disturbances, and psychological distress. They can also contribute to increased anxiety and depression.

Marin County Risk of Heat-Related Impacts 

HeatRisk differs based on individual impact. Heat sensitive groups include, older adults, those who work or exercise outdoors, infants and children, individuals experiencing homelessness, and individuals with a chronic medical condition. Protect your health with the guidance below or refer to The below flyers are available in English and Spanish


Community Resilience and Climate Adaptation

Cooling Tips

  • Slow down. Plan outdoor activities before noon or in the evening.
  • Wear lightweight, loose-fitting, light-colored clothing and a wide brimmed hat. Use sunscreen with a SPF of at least 15.
  • Stay indoors as much as possible.
  • Take cool baths or showers.
  • Place a damp towel around your shoulders to reduce body heat.

Keep Your House Cool

Learn How to Create an Energy Efficient Home

  • If air conditioning must be used, shut doors to unused rooms. Keep AC thermostats set at 78 F degrees or higher when home.
  • If air conditioning is not being used, stay on the lowest floor.
    • Use an energy-efficient fan. Set up your fans in windows or hallways so you can create a cross breeze that will draw in cooler air from the outside (or a cooler part of the house) to the warm areas.
      • Fan Hack: Fill a mixing bowl with ice or an ice pack, and put the bowl in front of a fan. Turn the fan on, and the air will mimic a chilly, misty breeze.
  • Consider energy-efficient window coverings.
  • Keep shades down and blinds closed, but windows slightly open. If safe, leave windows open at night.
  • Switch off unnecessary lights.
  • Keep many bottles of water in the refrigerator.
  • Bake and wash at night.  Use your microwave to heat food instead of your oven. Large appliances give off significant amounts of heat.

Safety Tips

  • Air out hot cars before getting into them.
  • Drink more fluids than usual even if you do not feel thirsty. Water is the safest liquid to drink during heat emergencies. Avoid drinks with alcohol or caffeine; they increase the heat's effects on your body.
  • Eat small meals and eat more often. Avoid foods that are high in protein, which increases metabolic heat.
  • Avoid using salt tablets unless directed to do so by a physician.
  • If you take diuretics, ask your healthcare provider about a lower dosage during hot weather.

Warning Signs of Heat Problems

Heat Exhaustion

When body fluids are lost though heavy sweating, blood flow to vital organs is reduced. This results in a mild form of shock. If not treated, the victim may suffer heat stroke.


  • Cool, moist, pale or flushed skin
  • Dizziness
  • Heavy sweating
  • Exhaustion
  • Headache
  • Nausea or vomiting


Get the person to a cooler place. Remove or loosen tight clothing and apply cool, wet cloths and ice packs. If the person is conscious, give cool water to drink. Make sure the person drinks slowly. Give a half glass of cool water every 15 minutes.  Contact a health care provider for follow up or call 911 if no improvement.

Heat Stroke

Heat stroke is life-threatening. The victim's temperature control system, which produces sweat to cool the body, stops working. The body temperature can rise so high that brain damage and death may occur.


  • Hot, red skin
  • Rapid, weak pulse
  • Little or no sweating
  • Rapid, shallow breathing
  • Changes in consciousness
  • High body temperature


Call 911. Move the person to a cooler place. Quickly cool the body. Immerse victim in a cool bath, or wrap wet sheets around the body and fan it. Use ice packs. Watch for signals of breathing problems. Keep the person lying down and continue to cool the body. If the victim refuses water or is vomiting, or there are changes in the level of consciousness, do not give anything to eat or drink.