WEATHER
What is CalHeatScore? How can Californians use the public health tool?
Ernesto Centeno AraujoUSA TODAY NETWORK
July 29, 2026, 3:49 p.m. PT
July, one of the hottest months of the year for California, is wrapping up, but the heat continues. What tools do Californians have to better understand rising temperatures?
The California Communities Extreme Heat Scoring System, or CalHeatScore, is an online public health tool to help Californians stay informed about the heat,according to the California Environmental Protection Agency
The system ranks heat from a scale of 0 to 4, with the highest representing the most severe form of heat, the state agency said
Ranking heat this way can help people in heat waves best assess their health risk and what is needed to avoid heat-related illness
How does it work and how do I check my area?
How does CalHeatScore work?
CalHeatScore uses a heat-health ranking system with 0 represented as low, one as mild, two as moderate, three as high, and four as severe
Because of the diversity of California’s climate and communities, each ZIP code is given its own heat score rather than cities or counties receiving scores
While agencies like the National Weather Service may put out extreme heat warnings for entire regions, some areas within those regions may experience less heat, so the public health tool helps better localize recommendations
- CHS 0- Little to no heat-related health impacts are expected.
- CHS 1- A warm day. A minor increase in heat-related health impacts is expected among those sensitive to heat.
- CHS 2- A very warm day. A moderate increase in heat-related health impacts is expected among those sensitive to heat.
- CHS 3- A hot day. An increase in heat-related health impacts is expected for everyone, especially those without access to adequate cooling and hydration or those engaged in strenuous physical activity outdoors. This level of heat can pose a significant risk to health.
- CHS 4- An extreme heat day. A major increase in heat-related health impacts is expected for everyone, especially those without access to adequate cooling and hydration or those engaged in strenuous physical activity outdoors. This level of heat can pose a very serious risk to health.
On Wednesday, July 29, the CalHeatScore tool registered the ZIP Code 90290 in Topanga Canyon, just east of Calabasas, as a heat risk of four
The tool showed that an estimated 7,043 people would be affected by the heat and the maximum forecasted temperature would be 95 degrees. The record high for the day is 98° F, and its average high is 92° F
Its neighboring zip code, 91302, is just a few miles away and measured at a CHS 2, or moderate, on July 29. It has bout 24,040 people, and its forecasted maximum temperature was 92 degrees, the tool showed
How to stay safe during the heat
The National Weather Service has provided tips to prepare for the heat, stay cool, and help out when heatstroke occurs
How to prepare for a heatwave:
- Gather food, water, and medication, and keep them ready and in a safe place.
- Make a list of friends, family, or vulnerable neighbors to check on.
- Familiarize yourself with local cooling shelters or cool locations.
- Postpone any previously planned outdoor events.
What to do in a heatwave:
- Drink plenty of water.
- Avoid the sun and outdoor areas and seek shelter in an air-conditioned environment.
- If outdoors, take breaks and use the buddy system.
- Check on pets and keep them indoors or in cool and shaded areas.
Someone suffering from heatstroke may seem confused, experience dizziness, and may fall unconscious. When treating someone for heatstroke, make sure to call 911, move the victim to a cooler area, remove any extra layers, loosen clothing, and cool them down with water or an ice pack, the weather service said
Ernesto Centeno Araujo covers breaking news for the Ventura County Star. He can be reached at ecentenoaraujo@vcstar.com, 805-437-0224 or@ecentenoaraujoon Instagram and X
