Most, or all of them use a combined average of the many weather models. I’ve heard good things about AcuuWeather that Francois mentioned. I use Weather Underground, it’s owned by IBM and uses all the same models as everyone else plus it combines IBM’s own very good model. It’s been a few years since I got that information so things may have changed a bit since then. They all loose some ability to predict beyond a few days and are almost worthless beyond 5 days. That’s especially true where I live since our weather comes off the Pacific Ocean with less data points. Where Francois lives, they have a lot of data points to use across the continent so the predictions can be better. Hopefully one good thing that will come from AI will be better forecast modeling.
