Firstly the BBC site allowing you to enter your postcode for a bespoke forecast. It uses MeteoGroup data.
MetCheck This site uses the American forecast model data and allows you to make your own graphs of forecast weather parameters.
For rainfall see: http://www.raintoday.co.uk/ and rain alarm and yr.no is another good weather forecast web site in Norwegian.
Weather on line is another interesting site with historical data.
weather.co.uk is a site from the Weather Channel and gives a local forecast
www.xcweather.co.uk is a good site for visualising the wind field over the U.K. at the current time
http://www.wunderground.com/ has loads of maps of present and forecast weather using the American model.
Ant Veal's amateur's site here.
The Tornado storm research organistion site here.
http://www.wetterzentrale.de/ a german site with good graphics.
If you are driving in UK always worth checking the Highways
If you are travelling to Europe this site shows you if there are any weather warnings in place in your destination country, click here.
and if you are travelling to the U.S. this
site is worth a visit or want to go skiing then click here.
A cloud spotters web site is here.