It's a good theory, but show me the proof. There are many factors, including the general lack of cold(er) air. I'm probably most resistant due to someone blaming the Great Lakes on our night time temperatures, despite the high winds reducing the radiational cooling during that period. The effect of the Great Lakes on night time temperatures in NYC cannot be greater than 0.5 F degrees, if that. But since there are no calculations, it is only speculation...