You have already experienced it dozens of times. The weather application on your smartphone (iOS or Android) announces a long, beautiful sunny day. But when you step outside, you realize that it’s pouring rain! But you are not dressed accordingly.
But then how can applications, built by tech giants like Apple or Google, be so wrong? In reality, the answer is twofold and much more complex than one might first believe.
To understand their errors, you must first look at how these applications work. Both Apple and Google use data provided by NOAA, the equivalent of Météo France in the United States. They can cross-check these bulletins with those of the NWS (National Weather Service).
Although this information is as complete as possible, it is, as we will see at the end of the articles, by nature imperfect. Predicting the weather comes down to trusting mathematical models and probabilities. But since risk 0 does not exist, these predictions may turn out to be false.
A problem of human psychology?
And it is precisely these errors that we notice. Because the human brain hates contractions. You will not notify when the weather on your smartphone matches reality, but only when it does not. It’s unfair, but terribly human. So over 365 days a year, the few errors will appear obvious to you, when in reality they are few in number.
Predicting the weather, an everyday challenge
Because predicting the weather may be a very complex exercise, organizations like Météo France or NOAA do it very well, especially for short-term predictions (up to D+3). The French organization notably recalls that forecasts are twice as reliable today as in 1980 (when they were already far from being catastrophic).
But then, how can we explain the errors that we recurrently notice? First of all, with 365 days a year, even 98% reliability leaves room for 8 false ads, which our brains will not fail to notice.
But the problem doesn’t end there. Indeed, Météo France’s forecasts are based, as we said above, on mathematical models. We look at what has already happened in the past in a similar situation and we try to draw conclusions.
However, the truths of yesterday are not those of tomorrow, especially in our world hit hard by global warming. The climate is changing, that’s undeniable, and the weather is becoming more and more unpredictable. Météo France recognizes that global warming is a daily challenge to keep reliable forecasts.
To adapt to this new model, the organization’s calculations were revised last November, taking into account global warming and the meteorological butterfly effect that accompanies it.
