On Thursday, 10 September 2026, at 11 a.m., phones across Germany will sound the alarm, radio stations will interrupt their programmes, and wherever sirens still exist they will wail. Around 11:45 a.m. the all-clear follows. This is the national warning day, the "Warntag", a drill in which you have nothing to do. It is, however, the one chance a year to check for free whether a real warning would reach you at all. Here is what is triggered that day, what the signals mean and what you should check while it happens.
What exactly is triggered at 11 a.m.
The test warning is sent by the Federal Office of Civil Protection and Disaster Assistance (BBK) through the federal modular warning system to all connected warning channels at once. Those are:
- Cell broadcast to every phone logged into a German mobile cell.
- Warning apps such as NINA, KATWARN and BIWAPP.
- Radio and television, which display or read out the message.
- Digital city information boards and displays in public transport.
- Sirens and loudspeaker vehicles, but only where municipalities take part. Participation is voluntary, and many cities dismantled their sirens in the nineties. Since 2021 new ones are being installed again.
The warning day has been held since 2020, usually on the second Thursday in September. Its purpose is technical: the federal government checks whether the chain from the situation centre to the phone works, and the public is meant to have heard the signals once before hearing them for real.
Cell broadcast: the warning that needs no app
Cell broadcast has been in regular operation in Germany since February 2023 and is the most important addition of recent years. The warning is not sent to phone numbers but broadcast by the masts to every device in the cell, the way a radio station transmits. That means it needs no app, no registration and no mobile data connection, and it arrives even when the network is jammed with calls. Nobody learns who received the warning; the senders know no recipients.
For it to arrive, the phone must be switched on, must not be in flight mode and needs a reasonably current operating system. The alert levels can be seen in the settings: on the iPhone under Notifications at the very bottom, on Android under Safety and emergency or Emergency alerts. The highest level cannot be switched off; the lower ones and the test alerts can. Anyone who hears nothing on warning day looks there first.
NINA, KATWARN or cell broadcast?
| Channel | Reaches | Needs | Strength |
|---|---|---|---|
| Cell broadcast | Every phone in the affected cell | Nothing but network and a switched-on phone | Reaches guests, tourists, people without an app. Short text, no map. |
| NINA (BBK) | App users, for chosen places or the current location | App, internet, place selection | Detailed text, map, recommended actions, plus weather and flood warnings. |
| KATWARN | App users, depending on the municipality | App, internet | Some districts prefer to warn through it; NINA usually carries the messages too. |
| Siren | Anyone who hears it | Nothing | Wakes you at night. But only says "attention", not what is going on. |
| Radio (FM) | Anyone with a radio | Batteries or a crank | Works when power and mobile networks have failed. The crank radio post explains what matters. |
The sensible combination is cell broadcast plus one app, and for the app NINA is enough. It wakes you and tells you what to do; cell broadcast alone only tells you that something is happening.
Siren signals: two tones worth knowing
- Warning: a rising and falling wail, one minute long. Meaning: close windows and doors, switch on the radio or a warning app, listen for announcements. Not: drive off, collect the children from school, phone the neighbours.
- All-clear: a continuous tone, one minute long. The danger has passed.
A third tone, three short continuous tones with pauses between them, is the call-out for the fire brigade and is not aimed at you. Some municipalities additionally use voice announcements over the siren. What exactly applies where you live is on your city's or district's website; on warning day you will hear it.
What to check on warning day
Eleven on a Thursday morning is a poor time for drills, because most people are at work. Still, five things are worth settling, and most of them can be done from anywhere:
- Does the warning arrive on the phone? On every device in the household, including the children's and the grandparents'. If not: check the settings, update the operating system, switch off flight mode.
- Does the emergency radio find the right station? The regional public broadcaster is the one that carries the situation for your district when it matters. Note the frequency and stick it on the radio.
- Can you hear the siren? If yes: where is it, and is it still audible with the windows closed? If no: then you depend on phone and radio, and that is good to know.
- Does everyone know what the tone means? Explain the wail to children once, so they can place it when it is real. That is the actual drill.
- Is there a family plan? Who collects whom, where do you meet when the network is down, and is it written down? A note in the wallet is the fallback when the phone is dead.
If the phone stays silent
The most common reasons are unspectacular: flight mode, a device in a dead spot, an old operating system without cell broadcast support, or the alert levels were switched off at some point. Check the settings, update the system and switch on test alerts; then you will also receive the next test warning. If it stays silent, the device is unsuitable for warnings, and then the app is the answer, not a new phone. NINA runs on older devices too.
And when it is real
A warning is information, not an order to flee. The message says what has happened, where, and what to do; you read it to the end before doing anything. Usually the answer is: stay inside, windows closed, radio on, inform the neighbours. Everything beyond that depends on what you prepared beforehand. The emergency area in Keepilo holds the emergency plan, the emergency contacts and the checklists for that, offline and without an account, and the library answers questions even when the network collapses after the warning. Warning day is the day to run through it once, while it is still a drill.