Spring brings with it significant changes as Denver can be affected by air masses on all sides, whether arctic air from the north, which occasionally combines with Pacific storm fronts bringing snow to the city. In fact, as reported at Denver International, March is the second snowiest month, averaging of snow. Additionally, warm air from the Gulf of Mexico can bring the first thunderstorms of the season, and continental warm air can bring summer-like warm and dry conditions. The last freeze of the season on average falls on May 6.