Due to its coastal location, Long Island winter temperatures are milder than most of the state. The coldest month is January, when average temperatures range from , and the warmest month is July, when average temperatures range from . Temperatures seldom fall below or rise above . Coldest temp ever recorded on Long Island was on January 22, 1961. Long Island temperatures vary from west to east, with the western part (Nassau County, Queens, and Brooklyn) generally 2 to 3 degrees F (1 to 2 degrees C) warmer than the east (Suffolk County). This is due to several factors: the western part is closer to the mainland and more densely developed, causing the "urban heat island" effect, and Long Island's land mass veers northward as one travels east. Also, daytime high temperatures on the eastern part of Long Island are cooler on most occasions, due to the moderating effect of the Atlantic Ocean and Long Island Sound. On dry nights with no clouds or wind, the Central Part of Suffolk County and Pine Barrens forest of eastern Suffolk County can be almost 5 to 10 F (3 to 5 C) cooler than the rest of the island, due to radiational cooling. Average dew points, a measure of atmospheric moisture, typically lie in the range during July and August.