The most reliable weather forecast websites for our area are 3Bmeteo and MeteoSwiss.
How to guess the wet weather

The first one is good for the weather forecast around Varese (day by day and hour by hour)
However you can write another town or village in the white box on the top of the page.
It's in Italian language but the numbers are international!
You can see the temperatures farenheit/celsius as well.
The second one is good for the total precipitation in millimeters per hour within the next 24 hours.
What happens to a scheduled ride if the weather is really bad?
Assuming that a drop of rain is not a show stopper for any cyclists, we always want to prevent dangerous situations. Should the weather conditions be causing risk or simply be so lousy that any fun is out of sight, we will pospone the ride and will find a new solution.