We were there during the week from the end of February to the beginning of March this year. For the most part it was great, although there was one rainy day towards the end of our trip where the daytime high only got into the mid 40's. Sweatshirts are a pretty good idea at night... as a matter of fact, we didn't pack anything warmer than that. Then again, we are from a particularly chilly part of New Hampshire, and live in a drafty old house, so your needs may differ.
Hope this helps...
Chris