California Emergency Alerts: How to Sign Up in Every County
Only about 9% of San Diego County adults are signed up for AlertSanDiego. Here is the official emergency alert sign-up for every county in California, and why the alerts your phone gets automatically are not enough.
Reviewed by Aaron J. Farmer, licensed flood specialist CA License #0L75450 · Last reviewed November 6, 2026
About 9% of adults in San Diego County are signed up for AlertSanDiego, the county’s emergency alert system, according to county figures reported by the San Diego Union-Tribune in early November. That would be a low number in any year. It matters more this winter, with a very strong El Niño expected to bring heavy rain to Southern California and the county urging people to register before the storms arrive.
San Diego is not unusual. Every county in California runs an alert system like it, and most of them only reach the people who sign up. Below you will find what these systems do, how they differ from the alerts your phone gets automatically, and the official sign-up link for all 58 counties.
Jump to your county
Alameda Alpine Amador Butte Calaveras Colusa Contra Costa Del Norte El Dorado Fresno Glenn Humboldt Imperial Inyo Kern Kings Lake Lassen Los Angeles Madera Marin Mariposa Mendocino Merced Modoc Mono Monterey Napa Nevada Orange Placer Plumas Riverside Sacramento San Benito San Bernardino San Diego San Francisco San Joaquin San Luis Obispo San Mateo Santa Barbara Santa Clara Santa Cruz Shasta Sierra Siskiyou Solano Sonoma Stanislaus Sutter Tehama Trinity Tulare Tuolumne Ventura Yolo Yuba
Two kinds of alert, and why you want both
Wireless Emergency Alerts come from the cell towers in an affected area and reach every capable phone within range. You do not sign up and you are not charged. They are reserved for the most serious situations: imminent threats to life or property, AMBER Alerts and national emergencies. They are short, and they are not used for the smaller, local warnings that often come first in a flood.
County alert systems are the ones you register for. They send texts, emails and phone calls, and because you give them an address, they can warn a single neighborhood about a closed road, a creek rising, an evacuation warning or a shelter opening. That detail is the point. Flooding in a wet California winter is usually local: one street, one creek, one canyon below a burn scar.
Most county systems only reach a cell phone or email address that has been registered. AlertSanDiego, for example, can call listed and unlisted landlines automatically through the 9-1-1 phone database, but your mobile phone and email only get alerts if you sign up. If you no longer have a landline, the county has no way to reach you until you register.
How to sign up in five minutes
- Find your county below and open its sign-up link. All of them are free.
- Register your home address, and your work address too. Cal OES, the state’s Office of Emergency Services, advises signing up in both counties if you live in one and work in another. Add a school or an elderly parent’s address if the system allows more than one location.
- Confirm the registration. Most systems send a text or email to confirm. Some, including Imperial County’s, will not activate your profile until you reply to it.
- Leave Wireless Emergency Alerts switched on in your phone’s notification settings. The two systems work together, so you want both.
Emergency alert sign-up for every California county
These are the official links from the Cal OES county directory at calalerts.org/signup.html. The sign-up pages are run by companies the counties contract with, such as Everbridge, Genasys and Smart911, so the web address often does not look like a government site. Every link below comes from that directory or the county’s own website, and we checked each one on 6 November 2026. If a link ever stops working, the Cal OES directory is kept current.
Southern California
| County | Alert system | Official sign-up |
|---|---|---|
| Imperial | Imperial County Alerts | Sign up |
| Los Angeles | LA County emergency notifications | Sign up |
| Orange | AlertOC | Sign up |
| Riverside | Alert RivCo | Sign up |
| San Bernardino | San Bernardino County alerts (Smart911) | Sign up |
| San Diego | AlertSanDiego | Sign up |
| Santa Barbara | ReadySBC Alerts | Sign up |
| Ventura | VC Alert | Sign up |
Bay Area and Central Coast
| County | Alert system | Official sign-up |
|---|---|---|
| Alameda | AC Alert | Sign up |
| Contra Costa | Community Warning System | Sign up |
| Marin | Marin County alerts | Sign up |
| Monterey | Alert Monterey County | Sign up |
| Napa | Alert Napa County | Sign up |
| San Benito | San Benito County Alerts | Sign up |
| San Francisco | AlertSF | Sign up |
| San Luis Obispo | SLO County alerts (Smart911) | Sign up |
| San Mateo | SMC Alert | Sign up |
| Santa Clara | AlertSCC | Sign up |
| Santa Cruz | CruzAware | Sign up |
| Solano | Alert Solano | Sign up |
| Sonoma | SoCoAlert | Sign up |
Sacramento and the Central Valley
| County | Alert system | Official sign-up |
|---|---|---|
| Butte | Butte County alerts | Sign up |
| Colusa | Colusa County alerts (Rave) | Sign up |
| Fresno | Notify Fresno County | Sign up |
| Glenn | Glenn County alerts | Sign up |
| Kern | ReadyKern | Sign up |
| Kings | Kings County alerts (Smart911) | Sign up |
| Madera | Madera County Citizen Alert | Sign up |
| Merced | Merced County Citizen Alert | Sign up |
| Sacramento | Sacramento County alerts (Smart911) | Sign up |
| San Joaquin | SJReady | Sign up |
| Stanislaus | StanAware | Sign up |
| Sutter | Sutter County alerts (Smart911) | Sign up |
| Tehama | Tehama Citizen Alerts | Sign up |
| Tulare | AlertTC | Sign up |
| Yolo | Alert Yolo | Sign up |
| Yuba | Yuba County alerts (CodeRED) | Sign up |
Northern California and the Sierra
| County | Alert system | Official sign-up |
|---|---|---|
| Alpine | Alpine County Notify Me | Sign up |
| Amador | Amador County Emergency Alerts (Smart911) | Sign up |
| Calaveras | Calaveras County Resident Alerts | Sign up |
| Del Norte | Del Norte County Alert System | Sign up |
| El Dorado | El Dorado County Emergency Alerts (Smart911) | Sign up |
| Humboldt | Humboldt County Resident Alerts | Sign up |
| Inyo | Inyo County Alerts | Sign up |
| Lake | LakeCOAlerts | Sign up |
| Lassen | Lassen County alerts | Sign up |
| Mariposa | Mariposa County Resident Alerts | Sign up |
| Mendocino | Mendocino County Public Alert | Sign up |
| Modoc | Modoc County alerts | Sign up |
| Mono | Mono County Alert | Sign up |
| Nevada | Nevada County Emergency Alerts | Sign up |
| Placer | Placer County Citizen Alert | Sign up |
| Plumas | Plumas County Alerts | Sign up |
| Shasta | Shasta County Public Warning System | Sign up |
| Sierra | Sierra County Resident Alerts | Sign up |
| Siskiyou | Ready Siskiyou (Smart911) | Sign up |
| Trinity | Ready Trinity (Smart911) | Sign up |
| Tuolumne | Tuolumne Citizen Alert | Sign up |
Cities with their own systems
Some cities run a separate system alongside the county’s. If you live in one, sign up for both.
- City of Los Angeles: NotifyLA, separate from LA County’s system.
- Long Beach: Alert Long Beach.
Flood tools worth bookmarking
An alert tells you something is happening. These tell you what is coming, and they are worth checking before a big storm.
- National Weather Service. Enter your ZIP code for flood watches and warnings where you live.
- California-Nevada River Forecast Center. River level forecasts, if you live near a river or levee.
- Genasys Protect. Look up your evacuation zone. It is a private company’s map, but several counties, including Alameda, Riverside, San Mateo and Yuba, send residents to it.
- San Diego County’s El Niño page. The county’s own storm preparation hub.
- Our sandbag directory. Where to get sandbags in 43 California counties, with the official source for each.
One that is popular but not official: Watch Duty is a nonprofit app that tracks wildfires and flooding. Many people find it useful, but it does not replace your county’s alert system.
An alert buys you minutes. Insurance has to be in place first.
An alert is the last step of a flood plan, not the first. It can get your family and car out of the way. It cannot do anything for the house. And flood coverage cannot be bought once a storm is on the radar: a new NFIP policy takes 30 days to start, and a private policy as little as 7 days, commonly 10. Your homeowners policy does not cover flood at all.
If you are signing up for alerts because of El Niño, it is a good week to check your flood coverage too. Our guide to El Niño and California flood risk covers what this winter’s forecast does and does not mean, and what to do before a flood covers the rest of the plan.
Common questions
Do I have to sign up to get emergency alerts on my phone?
For the most serious threats, no. Wireless Emergency Alerts go to every capable phone in the affected area automatically. For the more detailed, neighborhood-level alerts your county sends, such as evacuation warnings, road closures and flooding updates, you usually have to register your mobile number and email.
Does it cost anything to sign up?
No. County alert systems are free. Some note that your carrier’s standard text messaging rates may apply. Wireless Emergency Alerts are also free.
I live in one county and work in another. Which should I sign up for?
Both. Cal OES advises registering in each county where you spend time. Many systems also let you add more than one address to a single account.
Why doesn’t the sign-up link look like a government website?
Most counties contract with a company such as Everbridge, Genasys, Smart911, Rave or CodeRED to run their system, so the sign-up page sits on that company’s site. To check a link is genuine, start from your county’s official website or the Cal OES directory at calalerts.org.
Is an app like Watch Duty the same as my county’s alerts?
No. Watch Duty is a nonprofit service and can be useful, but your county’s official system is the one that sends evacuation orders and warnings for your address. Use both if you like, but register with the county first.
Check your flood coverage while you are at it
We quote both the NFIP and the private market, and we will tell you honestly when the NFIP is the better fit for your home. Request a quote in about two minutes, or call 855-CAL-FLOOD (225-3566) to speak to a licensed flood specialist.
Sources: San Diego Union-Tribune, as reported by Governing, 5 November 2026, and KOGO News, 4 November 2026; County of San Diego, AlertSanDiego registration page; Cal OES county sign-up directory and Wireless Emergency Alerts FAQ at calalerts.org. All sign-up links checked 6 November 2026. Counties change their alert systems from time to time; if a link has moved, the Cal OES directory will have the current one.
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