What moderates much off the air temperature over northwestern Europe

Warm winds from the Gulf of Mexico travel eastward across the Atlantic Ocean and moderate the temperatures over northwestern Europe. The Gulf Stream is the reason for the difference in temperature when compared with the east coast of the United States

For example, in early April of 2009, I left the NY (about latitude 40.7) city area where the temperature was still in the mid 30's and 40's (fahrenheit) and travelled to Paris France (about latitude 48.9) which is quite a bit further north from the equator. The temps there were in the 60's and low 70's. The trees and flowers were in bloom like they are in May in NY. I was amazed (and very happy as our trip (mostly walking) was great. This is due to those Gulf Winds.