North Carolina's climate varies from the Atlantic coast in the east to the Appalachian Mountain range in the west. The mountains often act as a "shield", blocking low temperatures and storms from the Midwest from entering the Piedmont of North Carolina. Most of the state has a humid subtropical climate (Köppen climate classification Cfa), except in the higher elevations of the Appalachians which have a subtropical highland climate (Köppen Cfb). The USDA hardiness zones for the state range from zone 5a (-20 °F to -15 °F) in the mountains to zone 8b (15 °F to 20 °F) along the coast. For most areas in the state, the temperatures in July during the daytime are approximately . In January the average temperatures range near . Precipitation There is an average of forty-five inches of rain a year (fifty inches in mountainous regions). July storms account for much of this precipitation. As much as 15% of the rainfall during the warm season in the Carolinas can be attributed to tropical cyclones. Mountains usually see some snow in the fall and winter. Moist winds from the southwest drop an average of of precipitation on the western side of the mountains, while the northeast-facing slopes average less than half that amount. Snow Snow in North Carolina is seen on a regular basis in the mountains. North Carolina averages of snow per winter season. However, this varies greatly across the state. Along the coast, most areas register less than per year while the state capital, Raleigh, averages . Farther west in the Piedmont-Triad, the average grows to approximately . The Charlotte area averages approximately . The town of Boone, North Carolina, located at an elevation of 3,333 feet in the northwestern part of the state, averages approximately 45 inches of snow per winter season. The mountains in the west act as a barrier, preventing most snowstorms from entering the Piedmont. When snow does make it past the mountains, it is usually light and is seldom on the ground for more than two or three days. However, several storms have dropped or more of snow within normally warm areas. The 1993 Storm of the Century that lasted from March 11 to March 15 affected locales from Canada to Central America, and brought exceptionally heavy snow to North Carolina. Newfound Gap received more than of snow with drifts more than , while Mount Mitchell measured over of