Just realised I didn't answer "how warm is it". The nights can be cold - sometimes down to freezing, even on the coast. Go inland 20 or 30 miles, and it will be freezing most nights. You will need some form of heating in the van. On many days, it's warm enough to take coffee outside by ten in the morning, but it can also rain. This last February/March we had two sessions when it rained continuously for more than 48 hours. But this year's weather generally, wasn't as good as previous years.