What to know about the UK’s national emergency alert system

The system is designed for use during the most likely emergencies to affect the UK

The UK’s national emergency alert system is designed to warn the public if there is a danger to life nearby.

When sent, mobile phones connected to 4G and 5G networks will vibrate and emit a siren sound for up to 10 seconds. Some smartphones also read out the message to recipients. The alarm will also sound even if the device is set to silent.

Phone users will be prompted to acknowledge the alert by swiping or clicking the message before being able to continue using their device.

The system, which is modelled on similar schemes in the US, Canada, the Netherlands and Japan, is intended to be used in life-threatening situations, including flooding and wildfires.

It has been tested twice, in April 2023 and September 2025.

Mobiles connected to 4G and 5G networks will vibrate and sound for around 10 seconds (PA)

Prime Minister Sir Keir Starmer confirmed the success of the exercise in 2025, writing on X: “Tens of millions of phones successfully sounded across the country during today’s Emergency Alert test.

“This is an important step in keeping people safe during national emergencies.”

The government has used the system to issue real warnings five times, including in January 2025 during Storm Eowyn, to warn people in Scotland and Northern Ireland about severe weather.

Approximately 3.5 million people across Wales and south-west England received an alert during Storm Darragh in December 2024.

A 500kg unexploded Second World War bomb found in a Plymouth back garden triggered a warning to some 50,000 phones in February 2024.

Cyprus Avenue in east Belfast after damage caused by Storm Eowyn (PA)

Messages can be targeted to relatively small areas to pinpoint those at risk.

Around 15,000 phones were alerted during flooding in Cumbria in May 2024, and 10,000 received a warning during flooding in Leicestershire in January 2025.

The system is designed for use during the most likely emergencies to affect the UK and warnings would also be transmitted on television, radio and locally by knocking on doors.

The AA recommends that drivers do not interact with the message until stopped in a safe place with the engine switched off.

There are concerns that the sound could reveal hidden phones belonging to domestic abuse victims, and groups are advising them to opt out of the alert.

To opt out, iPhone users should go to settings, search for “Emergency Alerts”, and turn off Severe & Emergency Alerts.

Android users can do the same by searching “Emergency Alerts” in settings and switching off Severe & Emergency Alerts.