Anyone who has been caught out in a yacht in bad weather knows the importance of checking the weather before heading out. These links provide up to date weather forecasts if you're planning to go out sailing:

UK Shipping Forecast & Gale Warnings
Updated twice daily and issued by the Met Office

UK Shipping Forecast Guide
Guide to the understanding the Shipping Forecast

Inshore Waters Forecast & Strong Wind Warnings
Updated twice daily and issued by the Met Office

High Seas Forecast & Storm Warnings
Includes storm warnings in force, coastal forecasts and an outlook for the next few days.

Sailing Weather Online
Large selection of charts and satelite maps covering most of the globe, ideal if you're planning that Trans-Atlantic voyage.

AccuWeather
15 day local forecast, tide tables, and a 3 day sailing forecast, what else do you need?

Bramblemet
Regularly updated weather reports from Bramble Bank.

Cambermet
Regularly updated weather reports from Chichester Harbour.

Chimet
Regularly updated weather reports from Chichester Bar.

Shoreham Weather
This site provides real-time weather, forecast data and climatic data for Shoreham-by-Sea, West Sussex.

Sotonmet
Regularly updated weather reports from Southampton Dockhead.