Thanks for the answers!
So, it is every two hours. Unfortunately, this is the standard for the Yahoo! Weather API these days.
Isn't really, because my last report is PM, and the first report is AM.
Now the weather report refreshed is 07 pm CET, now it is two hours differents really...
Today morning at CET 10:00:00 (AM) the last provider update is CET 07:00 PM...