With Pokemon GO’s recent update, weather plays a part in how frequent and powerful the local Pokemon are. Or they would if it didn’t frequently think the area is a disaster. Many players have been reporting that “extreme weather” has been raining on their Pokemon parade.
When the game believes you are in extreme weather, it considers it hazardous. This means the local Pokemon will be hiding because “Pokémon seem to dislike these conditions.” The issue is that what the game considers extreme weather isn’t that extreme. Players with light rain, fog, or even expected snowfall of any variety is enough for the game to consider extreme. Since this makes Pokemon rare to spawn, it’s been hindering many players’ gameplay.
It’s not surprising at this point to hear that Niantic is having trouble with bugs in their game. Hopefully this also means it will be resolved soon enough. Until then, we are at the whim of anything other than the occasional sunny day.