A week before going away on holiday I try and monitor the weather at my destination, to get an understanding of the climate. Finding a live web-cam can also assist in getting an understanding of the weather patterns.
A few of the web-sites I use: http://www.metoffice.gov.uk/weather/uk/radar/
http://www.xcweather.co.uk/ This site can be used for other countries.
http://www.wunderground.com/q/zmw:00000.1.06380 Can help with time differences, sun rise and set times. Plus web-cam links.
http://www.netweather.tv/ it has a video forecast with Michael Fish.