UK mobile users are being reminded that a test of the national Emergency Alerts system will take place this weekend.
The system sends alerts to mobile phones and tablets to warn of any danger to life, such as from extreme weather.
To be compatible, a device must be an iPhone running iOS 14.5 or later, or an Android phone or tablet running Android 11 or later.
During the test, which is scheduled for Sunday 7 September 2025 at 3pm, devices will make a loud siren-like sound and vibrate, even if they’re on silent. Alerts will not be received if a device is turned off or in aeroplane mode.
In an actual emergency, in addition to making a sound, the device would also display instructions on what people should do to stay safe.
The government website has instructions on how to opt out.