Keep Your Cool: UK to Conduct Nationwide Emergency Alert Test on Sunday at 3PM

Millions of mobile phones across the United Kingdom will emit a loud siren and vibrate for up to 10 seconds at 3pm this Sunday as part of a planned nationwide test of the emergency alert system, government officials confirmed.

The test is part of the UK’s ongoing efforts to ensure the system can deliver rapid alerts in the event of national or regional emergencies. All mobile phones connected to 4G and 5G networks will receive a message stating clearly that the alert is only a test.

Image Source: Cabinet Office UK

This marks the second national test of the UK emergency alert system, following its initial rollout in 2023. Since then, the technology has been used five times for real emergencies, including extreme weather events and a wartime ordnance incident.

Among its real-world deployments:

• In February 2024, a 500kg unexploded WWII bomb discovered in Plymouth triggered an alert to around 50,000 phones.

• During Storm Darragh in December 2023, 3.5 million alerts were sent to residents in Wales and southwest England.

• Severe flooding in Cumbria (May 2024) and Leicestershire (January 2025) prompted alerts to 15,000 and 10,000 devices, respectively.

• The system was also used during Storm Eowyn in January 2025 to issue targeted warnings in Scotland and Northern Ireland.

The alerts are designed to reach people in specific areas at risk and are sent alongside traditional emergency broadcasts via TV, radio, and door-to-door notifications. Government officials say the technology could prove vital in cases such as severe flooding, fires, industrial accidents, or other life-threatening events.

Work and Pensions Secretary Pat McFadden urged the public not to panic. “I know Brits will keep their cool when phones across the UK make a siren-like noise at 3pm. It’s important to remember this is only a test, just like the fire drills we all do in our schools and workplaces,” he said.

Emergencies can happen at any time and it’s important we’re prepared.

Ahead of the nationwide Emergency Alerts test at 3pm on Sunday, @patmcfaddenmp visited @covcampus’s Simulation Centre to meet apprentices training in emergency response, helping to protect the UK. pic.twitter.com/C9Y5yi215a

— Cabinet Office (@cabinetofficeuk) September 5, 2025

The Cabinet Office has also held discussions with domestic abuse charities to ensure vulnerable individuals are aware of how to opt out of receiving the alert on hidden or secondary devices.

After the drill, government agencies will review system performance in coordination with mobile network operators.