Hello
It depends very much on nwhat info you are looking for and what area.
For solent wind and sea historical data for the past year try http://www.chimet.co.uk/
Neil
The excellent Weather Underground site lists Plymouth. If you scroll down the page to the "History & Almanac" box, you can enter a date and see what the weather was on that day. When you see that data, you then will also see buttons allowing you to select a weekly or monthly view.