Under the Köppen climate classification, Long Island lies in a transition zone between a humid subtropical climate (Cfa) and a hot-summer humid continental climate (Dfa). The climate features hot, usually humid summers with occasional thunderstorms, mild spring and fall weather, and cool winters with a mix of snow and rain and stormier conditions. Spring can be cool due to the relatively cooler temperatures of the Atlantic Ocean and occasional blocking. Thunderstorms rarely form directly over Long Island, but can form over inland areas and then move eastward. Some storms may weaken as they approach Long Island due to the moderating effects of the Atlantic Ocean. The ocean also brings afternoon sea breezes to the immediate South Shore areas (within ) that temper the heat in the warmer months. The temperatures south of Sunrise Highway (NY Route 27) tend to be significantly cooler than the rest of Long Island in the spring and summer months because of the relatively cooler temperatures of the Atlantic Ocean. Long Island has a moderately sunny climate, averaging 2,400 to 2,800 hours of sunshine annually.