You will hear a lot about why Clinton did well tonight, but here is something that should be added to the list. Hillary Clinton's strongest support is with women 50+;  I may be accused of being sexist or ageist for saying this, but I think more then any other group, mature women (mature is the best euphemism I could come up with for old) hate the cold. The really warm temperature's made it  easy for this voting bloc to come to the polls today and I think that is helping Clinton a lot. The other angle that you are going to hear a ton about is that New Hampshire voters to did not want to go with the flow of what the national media was saying and wanted to make sure to keep this a 2 person race.
On a side note, here is a link to one of the better blogs I have found when it comes to NH politics:
http://graniteprof.typepad.com/