Weather is Crazy here
Answers
My experience is that the game weather tends to lag the real weather. But that might just be an artifact of where I live vs. where my local (game) weather is predicted and observed.
So I'd say ignore the real weather, pay attention to what the game says. And I can't wait until they start giving the poke-weather forecast on the evening news, ....
In my home village in Spain last Saturday I got accurate weather (Partly Cloudy) followed suddenly by Extreme for many hours, it was only freezing a bit.
Visiting New Orleans this week, it's been Clear and then Partly Cloudy, pretty correct, but last afternoon it turned overcast in real life, which was not picked up by the game. As a meteorologist I would prefer the game weather to be as predictable as real life ;)
On the other hand that resulted in my first Tauros (CP 1904) and Zangoose (CP 1949!) to return with me to Europe.