Having looked at a few areas in the North this weekend on www.metcheck.com, I would say that the wind speed on Sat/Sun is far too strong for the majority of family or non-specialised tents...be warned!
If you can avoid being out in the wind, then do. It isnt very pleasant lying there waiting for the tent to land on your head and hearing the trees creeking all around you!
If i am planning a weekend away i always check on metcheck before booking. Fairweather camper i know but better safe than sorry!
------------- Debbie
June 2010 - Ashfield Caravan Park, York
August 2010 - Thorpe Hall, Rudston