The UK Government has confirmed details of the second ever national test of the emergency alert system
Every mobile phone in the UK will be sent an emergency alert at the same time in what will be only the second ever national test of the system. The emergency alerts system is used to warn if there’s a danger to life nearby, including extreme weather, and allows vital information and advice to be sent to people rapidly in an emergency.
There are approximately 87m mobile phones in the UK.
During the test, mobile phones will vibrate and make a loud siren sound for roughly ten seconds, even if they are set to silent. A message will also appear on phone screens, making it clear the alert is only a test.
It will be sent, the UK Government say, at 3pm on Sunday, September 7. For our free daily briefing on the biggest issues facing the nation, sign up to the Wales Matters newsletter here
Emergency alerts work on all 4G and 5G phone networks in the UK and phones or tablets do not have to be connected to mobile data or wifi to get alerts. However, you will not receive alerts if your device is turned off; connected to a 2G or 3G network; wifi only; or not compatible.
The emergency services and the UK Government do not need your phone number to send you an alert.
The UK Government say it is being planned to make sure it works optimally and to familiarise the public with the alerts. This is in line with standard practice in other countries, such as Japan and the USA.
The wording will be published before the test, the UK Government has said.
Ahead of the national test, the government will be running a public information campaign to notify people that the test is taking place, including communications targeted at vulnerable groups, such as victims of domestic abuse who may possess a concealed phone.
Pat McFadden, Chancellor of the Duchy of Lancaster, said: “Emergency Alerts have the potential to save lives, allowing us to share essential information rapidly in emergency situations including extreme storms.
“Just like the fire alarm in your house, it’s important we test the system so that we know it will work if we need it.”
Since the first national test of the emergency alerts system in April 2023, five alerts have been sent, including during major storms when lives were at risk.
The largest ever use of the system saw approximately 4.5 million people in Scotland and Northern Ireland receive an alert during Storm Éowyn in January 2025, after a red weather warning was issued, meaning there was a risk to life.
Approximately 3.5m people across Wales and the south west of England received an alert during Storm Darragh in December 2024.
Other activations have included when an unexploded World War II bomb was discovered in Plymouth, as well as during localised flash flooding in Cumbria and Leicestershire.