I stopped trusting the weathermen years ago. I missed a lot of riding time because I was worried about even the slightest chance of rain.
Now I have a thermometer outside my window to check the temperature and will glance at the 5 day forecast and look at the chance of precipitation percentages.
Since most of my commutes are only a few miles I have some cheap Field & Stream Rain Pants and Jacket that cost about a total of $60.