I agree with the OP, at least for Google. For whatever reason, the weather information for my area in Japan is not even close -- for example off by 15 degrees C some days. It has either confused my location for another one, or it's just coming up with random data. It's actually a bit hilarious because whatever data they are using, it's the same data that Pokemon Go is using. I played that game for a while and the two agree exactly. I could get all the rain Pokemon without a cloud in the sky...