Which apps warn me about floods and heavy rain?

Thunderstorms, major fires, heavy rain: Warning apps such as Nina or Katwarn inform their users about very different events, right up to a real disaster. But you can’t rely on one app alone. Each has its own area of application.

The cell phone buzzes, a notification lights up: “Warning, severe weather with heavy rain in area XY” it reports. A tap on the screen and detailed information follows. This is actually how all disaster warning apps that you can download for your smartphone work.

The four major disaster warning apps in Germany

Warning apps are a contemporary channel for messages in the event of a disaster, says Michael Judex of the Federal Office of Civil Protection and Disaster Assistance (BBK). With them, warnings ideally reach the millions of smartphones active in Germany with pinpoint accuracy. Users can see at a glance what danger is imminent at their own location or in the region they have set.

Four major disaster warning apps are currently available for Germany. But installing one of these apps is by no means the end of the story. Because there are major differences in what individual ones warn about. And not every app warns nationwide. At first glance, the differences are not necessarily apparent. So here’s an overview of the four disaster warning apps Nina, Katwarn, Biwapp and Warnwetter.


Nina was developed by the BBK. The name stands for “emergency information and news app.” The disaster warning app is an output channel of the satellite-based Modular Warning System, through which radio stations, for example, also receive official warnings, Michael Judex explains. The federal government, which only issues warnings for major national hazard situations, has made the system available to the states for their warning tasks.

In the case of dangers from the area of disaster control, for example severe weather or flooding, the federal states are responsible and can issue warnings independently via Nina. Nina receives weather warnings from the German Weather Service. In many federal states, the disaster warning app also warns of less widespread dangers. For example, of the defusing of world war bombs. Here, the responsibilities vary depending on the federal state. A map showing the districts and cities that warn of local hazards via their own control centers or the respective Ministry of the Interior is available on the BBK website.

Via the “Emergency Tips” category, users can also find out about the right way to behave in an emergency in the app, regardless of any acute danger.

Smartphone battery quickly empty? A practical function can help!


Katwarn was developed by the Fraunhofer Institute Fokus on behalf of public insurers. Like Nina, it is one of the better-known disaster warning apps in Germany. It offers regionally different functions and issues nationwide warnings from the German Weather Service. For statewide hazards, Katwarn users in Hamburg, Berlin, Rhineland-Palatinate, and Saarland receive notifications. For some counties and independent cities, there are regional messages. They can be viewed on the Katwarn website.

One disadvantage is that users can enter a maximum of seven zip codes for which they want to be warned, in addition to their own location. This severely limits the range, especially in large cities with many zip codes. Katwarn offers themed subscriptions in cooperation with the respective event organizers: This means that visitors to festivals or trade fairs are kept up to date about the event.


Biwapp stands for “citizen info and warning app.” The app not only warns of major disasters, but also provides information about school cancellations, manhunts or traffic accidents. However, this is only possible if the responsible schools, offices or police authorities feed the app with the necessary information.

A practical feature is that the individual categories can be switched on and off. If you don’t have children, you probably don’t care if school is canceled. Users can also send an emergency call to the police and fire department via the disaster warning app. In doing so, it shows the current address and location.

DWD Warning Weather

If users primarily want to find out about the weather, they can use the Warnwetter application, an app from the German Weather Service. It warns of black ice or storms, for example, and provides detailed information about the current weather in Germany.

The developers of the various disaster warning apps are already cooperating with each other, explains Jakob Rehbach from BBK. In the future, for example, the messages of the Modular Warning System will become part of all warning apps. “The common goal is to inform the population as comprehensively as possible.”

All four disaster warning apps are available free of charge for Android and iOS. However, users should not make one mistake: relying solely on the app. “In general, messages via app are only one piece of the puzzle when it comes to warnings,” says Silvia Darmst├Ądter of the German Firefighters Association. They are never the sole means of warning, she says, but only a useful supplement to sirens, television and radio.

In Brazil: OTT shows shooting incidents

In contrast, the Brazilian app OTT shows how the topic of security alerts via app can be taken a step further: it displays crimes in the city of Rio de Janeiro in real time. Shootings, muggings, rapes – the app pinpoints the places that passersby should avoid. The information comes from the users themselves: Anyone who observes a crime can enter directly into the app where it is taking place and what it is about. This creates a map of crime.