Every ten minutes, I make an API call to the SMHI's API with the GPS coordinates less than 1 km from here (which cannot possibly matter for accuracy, but does for privacy). SMHI is the Swedish weather forecast "ministry" or however one would translate it. They've been collecting weather stats since the mid-1700s, so you'd think they would be pretty skilled by now. I think they have some of the oldest weather data in the world, but don't quote me on that.
I don't really care about the temperatures, but I do look out for rain. In fact, I automatically clear and update my little "calendar" in my "control panel" with little icons for when this API claims that it will rain in the next 7 days, so that I constantly know how long it's left until the next time it rains. In theory.
I love rain.
Well, yesterday, my calendar was full of those sweet rain icons. I rubbed my hands and started looking forward to a nice week full of wonderful rain, yet now when I wake up, it has updated to be six full days left until the next time it rains again. And this is far from the first time. In fact, it happens all the time. They basically seem to have no idea whatsoever when it's going to rain, until just before it starts.
Are modern weather forecasts this inaccurate? Are they just particularly incompetent over at SMHI? I did integrate another, international API. I guess I should write some mechanism to compare their data with SMHI's. However, I suspect that the international API might well just use SMHI's data for coordinates within Sweden, and I'm not exactly eager to figure out how to make such a comparison.
Is rain forecasting really this inaccurate still? Isn't one week a pretty reasonable window to expect accurate weather data?
This makes me really wonder how accurate those "farmer's calendar" predictions were. It would interest me to see how right they have been compared to modern "scientific" weather forecasting.