I know there are better rain-forecast sources than "hourly forecast" websites. What's the best such source?
http://www.weatheroffice.gc.ca/radar/index_e.html

Use the moisture radar, it's your best tool to see when the rain is coming and when it's going with great detail. If you take the time to familiarize yourself with it you'll start to get a feel for how different types of rain look on the radar and where it's going to hit.