I have said for a long time your best just looking out the window instead of listening to the weather forecast's. The BBC where making a big fuss of the new equipment at the met office a few weeks ago, just recently the forecasts have been wildly optomistic.

The most accurate weather forecast I have found is at yr.no

The forecast for Brum is http://www.yr.no/place/United_Kingdom/England/Birmingham/hour_by_hour.html and is usually pretty good. It covers the world and I have used it on my extensive travels and it is generally spot on.