The U.S. Department of Homeland Security’s Federal Emergency Management Agency (FEMA), in coordination with the Federal Communications Commission (FCC), conducts nationwide tests of the Wireless Emergency Alert System (WEAs) and Emergency Alert System (EAS). WEAs are designed to warn the public about dangerous weather, missing children, and other critical situations through alerts on cell phones. The EAS system is also used in major emergencies to broadcast emergency information via radio and television.
The public is generally notified 24 hours in advance of these tests. Only cell phones who have the test setting enabled will receive the WEA test. You can opt-in for tests online.
Opt-in for WEA test alerts on Android and iOS phones.