OK, I have already written about this once before (back in 2009) but I have found this one small thing that you can do before a ride on what looks like a rainy day to be so simple and helpful that I just have to do an update and mention it one more time.
Check your Local Weather Radar before your ride. I have a “favorites” location added in my browser for the online weather radar specifically for my area and I set it to be animated when I go there, but you could also just go to the weather channel on TV for a quick update if you prefer.
This is the most helpful on cloudy days when it looks like it might rain or on days when the forecast is calling for rain. Often times it is just cloudy and there are no major rain clouds in the area or when the forcast says rain it might just be a very small percentage of a chance that it is really going to rain.
There are many days (such as just a few days ago) when it really looked like it was going to rain and I really wanted to get out and ride. Well, I checked the local radar on the internet and saw that there was no major rain heading my within the last radar updates (usually 1/2 hour to an hour) so even if it sprinkled a little on my ride, I was very confident that I would at least not get soaked (and most of the time it did not even rain at all). If you need to check more time, for a longer ride, just zoom out for a wider view.
There are other times when I saw rain coming on the radar and was able to accurately predict when it would hit the area where I would be riding and adjust my ride to the time that I had available. It’s amazing how well this works and how accurate it is.
Anyway, I hope this helps and it is really quite a simple helpful way to plan your rides.
For some other related bike ride and weather information. Here’s a link to my 2009 post on this subject and a link to some other helpful hints on what to wear for your ride in different weather conditions.