Learning to read radar is phenomenally helpful in determining whether or not it will rain. It's not very difficult either.

A few years ago I was able to stop my friend's outdoor wedding (on the terrace as opposed to the hall, the venue had both ready) from getting rained out by reading the radar and catching a small pocket storm that had formed and coming right towards us. Sure enough it down poured, but everyone was inside for the ceremony. Reading just the weather report, there wasn't even rain forecasted.