San Mateo County, CA Weather Alerts
Every National Weather Service alert issued for San Mateo County, California, pushed to your phone within moments — county code CAC081, forecast zone 3 zones (CAZ508, CAZ509, CAZ512). Free with StormCast.
Download on Google PlayHow the NWS identifies San Mateo County
These are the identifiers the National Weather Service uses when it issues a warning here. StormCast watches CAC081 directly rather than matching on place names, which is why an alert arrives whether you are in Atherton or anywhere else in the county.
NWS County Code
CAC081
Forecast Zones
3 zones (CAZ508, CAZ509, CAZ512)
Forecast Office
Monterey (MTR)
Radar Station
KMUX
Towns covered in San Mateo County
An NWS alert for San Mateo County applies to all 23 of these communities. You do not need a separate alert for each one.
River gauges in and around San Mateo County
StormCast tracks 12 gauges near San Mateo County. Set a flood-stage alert on any of them to get notified before the water reaches you.
- Lower Crystal Springs Reservoir at Dam
- San Mateo Creek below Lower Crystal Springs Reservoir NR San Mateo
- Pilarcitos Creek below Stone Dam NR Hillsborough
- Pilarcitos Creek above Stone Dam
- San Mateo Creek above Junction Box
- San Mateo Creek below Junction Box
- Pilarcitos Creek at Half Moon Bay
- Belmont Creek at Harbor Blvd at Old County Road
- Pilarcitos Lake
- Pilarcitos Creek below Pilarcitos Lake Spillway
- San Andreas Lake near Millbrae
- Green Hills Creek at Green Hill Country Club
Current conditions
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Alert types issued for San Mateo County
Tornado
Tornado Warning, Tornado Watch, Tornado Emergency and Severe Thunderstorm Warning.
How tornado alerts work →Flooding
Flash Flood Warning, Flood Watch, Flood Advisory and River Flood Warning.
How flood alerts work →Winter
Winter Storm Warning, Ice Storm Warning, Blizzard Warning and Winter Weather Advisory.
Winter warnings explained →Fire Weather
Red Flag Warning and Fire Weather Watch when conditions favor rapid fire spread.
Fire weather alerts →Heat & Cold
Excessive Heat Warning, Heat Advisory, Freeze Warning and Frost Advisory.
Frost & freeze alerts →San Mateo County weather alert questions
Which NWS forecast zone is San Mateo County in?
San Mateo County, California is NWS county code CAC081 and spans 3 forecast zones (CAZ508, CAZ509, CAZ512). Alerts for it are issued by the Monterey (MTR) Weather Forecast Office, and the nearest NEXRAD radar is KMUX.
Which towns in San Mateo County are covered?
All of them. NWS alerts are issued at the county and zone level, so a warning for San Mateo County covers every community inside it, including Atherton, Belmont, Brisbane, Burlingame, Daly City, El Granada, Half Moon Bay, La Honda, Loma Mar, Menlo Park, Millbrae, Montara, Moss Beach, Pacifica, Pescadero, Portola Vally, Redwood City, San Bruno, San Carlos, San Francisco, San Gregorio, San Mateo and South San Francisco.
Are there river gauges in San Mateo County?
Yes — StormCast monitors 12 river gauges in and around San Mateo County, including Lower Crystal Springs Reservoir at Dam, San Mateo Creek below Lower Crystal Springs Reservoir NR San Mateo, Pilarcitos Creek below Stone Dam NR Hillsborough. You can set a flood-stage alert on any of them and get a push notification when the water rises.
How fast are alerts for San Mateo County delivered?
StormCast polls the NWS alert feed every 30 seconds. When a warning is issued for CAC081, the push notification goes out within moments — even with your screen off.