WeatherSignal hacks your phone’s sensors to turn it into a weather station

What if your phone could directly read the temperature instead of relying on distant weather stations? It turns out Android phones can, in a bit of a roundabout way.
The WeatherSignal app crowdsources weather with the temperature sensors built into the batteries of Android-compatible phones. iPhone users can’t provide data, but they can use the app. Since its launch three months ago, researchers and the OpenSignal team behind the app have been monitoring its effectiveness. They found that in six major cities the app is accurate to within an average of 2.7 degrees. They published their work today in Geophysical Research Letters (subscription required). WeatherSignal app
The app works by comparing a battery’s current temperature to its normal temperature, which can be used to infer the environment surrounding the phone. Other factors can come into play though, such as running an energy-intensive game that causes a phone to heat up. To minimize error in temperature readings due to factors like these, WeatherSignal needs lots of phones submitting weather data that can then be averaged.
WeatherSignal’s accuracy is still hurt by a relatively low number of users. The six cities OpenSignal used to determine the app’s accuracy have an above average number of people submitting data, which means temperature readings are more likely to be more than 2.7 degrees off in other cities. Cofounder James Robinson said in a release that as the number of users grows, OpenSignal will need to fine tune readings in currently underserved cities based on weather station data.
“The ultimate end is to be able to do things we’ve never been able to do before in meteorology and give those really short-term and localized predictions,” Robinson said. “In London you can go from bright and sunny to cloudy in just a matter of minutes. We’d hope someone would be able to decide when to leave their office to get the best weather for their lunch break.”
There are only around three people providing data in San Francisco. Hopefully the number increases in the future, as the city’s microclimate-stricken citizens could use an app like this.