There are hundreds of different apps to help us decipher the whims of the weather. Often, the programs available by default on Apple or Android phones are the most used. But they are not always reliable.
The days of waiting for the weather report on television seem to be over. Today, many French people’s first instinct, when they wake up, is to look at the weather… on their smartphone. The only thing that doesn’t change is our ability to complain when a forecast turns out to be inaccurate. But can we trust the applications available on our mobile phones?
Take the example
On the evening of Thursday, September 9: four departments of Occitanie were on orange alert for thunderstorms. The forecasts of the Météo France application announced the end of this bad weather on the night of September 9 to 10, in Haute-Garonne and Ariège and a maximum daytime temperature of 24°C in Toulouse. Apple’s application was counting on the end of the storms around 10 p.m. and a maximum temperature of 25° in the Pink City… almost the same forecast.
If the weather on the phones seems to be reliable at “the moment t”, when we look at the more or less long-term forecasts, the differences are much more marked. Last year, Jonathan Porte, vice-president of AccuWeather, the weather forecast installed by default on Samsung smartphones, explained: “We are constantly integrating new datasets, and we are seeking to improve our algorithms”. Changes are therefore made very often to fill in some gaps.
For the day of Tuesday, September 14, for example, Météo-France announces heavy storms in Toulouse with an average temperature of 27°, when the iPhone application indicates stormy weather with a thermometer at 24°… i.e. 3 degrees of difference. Differences oscillate on average between 1 and 3° when we look at the forecasts over seven days.
Raw data without human interpretation
The weather “found (by default) on iPhone or Samsung smartphone does not use the same database as that used by Météo France. Most of these apps use the American model. Which is self-service, and not to the European model”, explains a forecaster to the 20 Minutes site. The difference between the models is explained by the choice of the territorial mesh. The American is wider and covers areas of 20km, while on the side of Météo France for example, the mesh is finer and therefore more precise in certain situations.
These data are raw outputs, adds the specialist. They are not appraised by a forecaster and are therefore very often not subject to any human interpretation. And it is this analysis that changes everything. Météo France forecasters must take into account other factors before sending their weather reports. Such as the direction and speed of the wind, an important data that can modify or supplement a forecast.
How can you be sure of your weather forecast? It is advisable to download several applications on your smartphone and compare the results. Among the best rated application libraries are Météo France, La Chaîne Météo, MétéoCiel, Yahoo Météo and WeatherBug. The choice is yours: there are more than 8,000 specialized applications on Android and 2,400 on iPhone.
