UK Emergency Alerts: the siren on your phone, explained
What the loud siren means, when the government sends Emergency Alerts, what a real one looks like, and how — and when not — to turn them off.
By Tom Rowland · Updated 20 July 2026 · Sourced to GOV.UK Emergency Alerts
What Emergency Alerts are
Emergency Alerts is a UK government system that broadcasts a warning and advice message to all compatible 4G and 5G mobile phones and tablets within a defined geographic area when there's a danger to life nearby. It works by cell broadcast, which means your device doesn't need to be connected to mobile data or wifi to receive one.
Because it's a broadcast, it won't reach every device: alerts aren't received on 2G or 3G-only phones, wifi-only tablets, devices that are switched off, or incompatible handsets. But for the great majority of modern phones, if there's a serious emergency where you are, your phone will tell you.
Your privacy is protected
A common worry is that this means the government is tracking your phone. It doesn't. The system doesn't need to know your phone number or your location, and no personal data is collected. Alerts are broadcast to all compatible phones in the target area rather than sent to individuals, so no one is identified or tracked.
Receiving an alert is also completely free — you can't be charged for it, and your phone doesn't need mobile data or credit to receive one.
What a real alert looks and sounds like
A real alert makes a loud, siren-like sound and vibrates for about 10 seconds — and it sounds even if your device is set to silent, which is deliberate. The on-screen message includes advice about what's happening and what to do, plus a phone number or a link to the GOV.UK website for more information. Alerts are sent in English, and may also be sent in Welsh in Wales.
Only the emergency services and government bodies that deal with emergencies can send them, and only for life-threatening situations such as severe flooding, wildfires and extreme storms. So if your phone blares that siren, the message is genuine and worth reading immediately.
The tests, and the real alerts so far
The first UK-wide test took place on Sunday 23 April 2023 at 3pm, sending a test message to most compatible phones across the country. The second national test followed on Sunday 7 September 2025 at 3pm — only the second nationwide test — and clearly stated it was a test with no action required.
Between those tests the system was used for real around five times, all during major storms. Storm Éowyn in January 2025 was the largest ever use, reaching approximately 4.5 million people in Scotland and Northern Ireland after a red weather warning, and Storm Darragh in December 2024 reached approximately 3.5 million people across Wales and South West England. It's a system that has already earned its keep.
Turning them off — and the one important exception
You can opt out, though the government advises against it for most people because alerts carry life-saving information. On an iPhone, go to Settings > Notifications, scroll to the bottom, and turn off Severe alerts and Extreme alerts. On Android, search your settings for "emergency alerts" and turn off severe and extreme alerts.
There is one situation where turning them off is the right call. Government guidance recognises that victims of domestic abuse who keep a concealed second phone may find it appropriate to switch alerts off, because the loud siren — which sounds even on silent — could otherwise reveal a hidden phone. If that applies to you or someone you're helping, that's the recognised exception.
Common questions
What is the loud siren on my phone?
It's a UK government Emergency Alert — a broadcast to phones in an area where there's a danger to life, such as severe flooding or storms. It's free, sounds even on silent, and the on-screen message tells you what to do.
Does the government track me or need my number?
No. Emergency Alerts use cell broadcast to every compatible phone in an area, so the system doesn't need your number or location and collects no personal data. No one is identified or tracked.
When has the system been used for real?
Around five times, all in major storms — most notably Storm Éowyn in January 2025 (about 4.5 million people in Scotland and Northern Ireland) and Storm Darragh in December 2024 (about 3.5 million across Wales and South West England).
Which phones receive Emergency Alerts?
Compatible 4G and 5G phones and tablets. Alerts aren't received on 2G/3G-only phones, wifi-only tablets, switched-off devices or incompatible handsets — worth checking if an older phone is someone's only device.
How do I turn Emergency Alerts off?
On iPhone, Settings > Notifications > turn off Severe and Extreme alerts at the bottom. On Android, search settings for "emergency alerts" and turn off severe and extreme alerts. The government advises keeping them on for most people.
Is there ever a good reason to turn them off?
Yes — the recognised exception is for domestic-abuse victims with a concealed second phone, since the loud siren (which sounds even on silent) could reveal a hidden phone. For almost everyone else, it's safer to leave them on.
Sources: GOV.UK — Emergency Alerts · GOV.UK — Emergency Alerts: opt out · GOV.UK — Second national Emergency Alerts test. PreparedBritain is independent and not affiliated with HM Government.
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