National Weather ServiceCaliforniaExtreme Heat WatchArchive to October 1, 2026
Extreme Heat Watches in California
The National Weather Service issued 18 extreme heat watches for California in 2025 and 22 a year on average in 2008-2025; in 2021-2025 it had the 1st most of any state. 2026 through September: 23, in line with the average of 22 for those months in 2008-2025. San Bernardino County-Upper Colorado River Valley was covered most often (56 times since 2008).
How many extreme heat watches does California get?
Every extreme heat watch that covered part of California. 2026 is an outline: the year is not over.
The numbers
| Year | Count |
|---|---|
| 2026 (through September) | 25 |
| 2025 | 18 |
| 2024 | 42 |
| 2023 | 30 |
| 2022 | 33 |
| 2021 | 54 |
| 2020 | 48 |
| 2019 | 20 |
| 2018 | 32 |
| 2017 | 28 |
| 2016 | 11 |
| 2015 | 8 |
| 2014 | 5 |
| 2013 | 9 |
| 2012 | 18 |
| 2011 | 10 |
| 2010 | 15 |
| 2009 | 6 |
| 2008 | 17 |
Source: Iowa Environmental Mesonet archive of National Weather Service watches, warnings and advisories (VTEC); National Weather Service. Data as of October 1, 2026.
When in the year does California get them?
Sum of 2008-2025; the busiest month is labelled.
Source: Iowa Environmental Mesonet archive of National Weather Service watches, warnings and advisories (VTEC); National Weather Service. Data as of October 1, 2026.
Where in California?
| County or forecast zone | Since 2008 | Since 2023 | Last issued |
|---|---|---|---|
| San Bernardino County-Upper Colorado River Valley | 56 | 10 | August 18, 2026 |
| Death Valley National Park | 54 | 12 | August 18, 2026 |
| Including the Mojave National Preserve | 53 | 10 | August 18, 2026 |
| Imperial Valley | 50 | 20 | August 18, 2026 |
| Cadiz Basin | 50 | 9 | July 23, 2026 |
| Santa Clarita Valley | 49 | 19 | October 2, 2026 |
| Morongo Basin | 49 | 8 | August 18, 2026 |
| Western Mojave Desert | 48 | 10 | July 23, 2026 |
| San Diego County Deserts | 47 | 17 | July 22, 2026 |
| Imperial County West | 47 | 20 | August 18, 2026 |
| Coachella Valley | 47 | 17 | July 22, 2026 |
| Chuckwalla Valley | 46 | 18 | August 18, 2026 |
The NWS issues these products for counties or forecast zones; a zone can be part of a county or a mountain range.
Source: Iowa Environmental Mesonet archive of National Weather Service watches, warnings and advisories (VTEC); National Weather Service. Data as of October 1, 2026.
The latest extreme heat watches for California in AreaZine's record
NWS San DiegoWatchSeptember 30, 2026
Extreme Heat Watch: San Diego County Coastal Areas, San Bernardino and Riverside County Valleys-The Inland Empire, San Diego County Inland Valleys and 3 more, CA
In force until 9:00 p.m. PDT, October 7, 2026
NWS Los Angeles/OxnardWatchSeptember 30, 2026
Extreme Heat Watch: Catalina and Santa Barbara Islands, Santa Clarita Valley, Ventura County Beaches and 16 more, CA
In force until 8:00 p.m. PDT, October 8, 2026
This list is AreaZine's record of the NWS alert feed, kept since April 6, 2026; the counts above come from the complete IEM archive.
Source: National Weather Service alerts (api.weather.gov).
What is an extreme heat watch?
An extreme heat watch means dangerous heat is possible in the coming days. It replaced the excessive heat watch in 2025. A watch means the conditions for the hazard are possible or favourable, but it is not yet happening: be ready to act if a warning follows. AreaZine's counts include the excessive heat watches issued before the change. The national record · Every warning type in California.