On September 20 at 1:18p.m. Central Time, FEMA will be conducting an annual test of the Emergency Alert System (EAS). For the first time however, the Wireless Emergency Alert (WEA) system will also be tested.
This means most citizens with cell phones will receive the test alert at the same time as the EAS test.
For more information on the WEA test, visit the FEMA website at https://www.fema.gov/news-release/2018/07/23/nationwide-test-emergency-alert-system-be-conducted-september-20-2018.
For information on how the WEA works, visit the FCC website at https://www.fcc.gov/consumers/guides/wireless-emergency-alerts-wea.