The geographical divisions of North Carolina are useful when discussing the climate of the state.
The coastal plain is influenced by the Atlantic Ocean, which keeps temperatures mild in winter and moderate in the summer. Daytime high temperatures on the coast average less than 89°F (32°C) during the summer. In the winter, the coast has the mildest temperatures in the state, with daytime temperatures rarely dropping below 40°F (4°C); the average daytime winter temperature in the coastal plain is usually in the mid 60s. Temperatures in the coastal plain rarely drop below freezing even at night. The coastal plain usually receives only one inch of snow or ice annually, and in some years there may be no snow or ice at all.
The Atlantic Ocean has less influence on the Piedmont region, and as a result the Piedmont has hotter summers and colder winters than the coast. Daytime highs in the Piedmont often average over 90°F (32°C) in the summer. While it is not common for temperatures to reach over 100°F (38°C) in North Carolina, when it happens, the highest temperatures are to be found in the lower areas of the Piedmont, especially around the city of Fayetteville. Additionally, the weaker influence of the Atlantic Ocean means that temperatures in the Piedmont often fluctuate more widely than the coast.
In the winter, the Piedmont is much less mild than the coast, with daytime temperatures that are usually in the mid 50s, and temperatures often drop below freezing at night. The region averages from 3 – 5 inches of snowfall annually in the Charlotte area to 6 – 8 inches in the Raleigh – Durham area. The Piedmont is especially notorious for sleet and freezing rain. It can be heavy enough in some storms to snarl traffic and collapse trees and power lines. Annual precipitation and humidity is lower in the Piedmont than either the mountains or the coast, but even at its lowest, the precipitation is a generous 40 inches per year.
The Appalachian Mountains are the coolest area of the state, with daytime temperatures averaging in the low 40s and upper 30s for highs in the winter and often falling into the teens ( – 9 °C) or lower on winter nights. Relatively cool summers have temperatures rarely rising above 80°F (27°C). Snowfall in the mountains is usually 14 – 20 inches per year, but it is often greater in the higher elevations. For example, during the Blizzard of 1993 more than 50 inches of snow fell on Mount Mitchell over a period of three days.
Severe weather occurs regularly in North Carolina. On average, the state receives a direct hit from a hurricane once a decade. Tropical storms arrive every 3 or 4 years. In some years, several hurricanes or tropical storms can directly strike the state or brush across the coastal areas. Only Florida and Louisiana are hit by hurricanes more often. Although many people believe that hurricanes menace only coastal areas, the rare hurricane, which moves inland quickly enough can cause severe damage. In 1989 Hurricane Hugo caused heavy damage in Charlotte and even as far inland as the Blue Ridge Mountains in the northwestern part of the state. On average, North Carolina has 50 days of thunderstorm activity per year, with some storms becoming severe enough to produce hail, flash floods, and damaging winds.
North Carolina averages fewer than 20 tornadoes per year. Many of these are produced by hurricanes or tropical storms along the coastal plain. Tornadoes from thunderstorms are a risk, especially in the eastern part of the state. The western Piedmont is often protected by the mountains, which break up storms up as they try to cross over them. The storms will often reform farther East. Also a weather feature known as “cold air damming” occurs in the western part of the state. This can also weaken storms but can also lead to major ice events in winter.
Monthly normal high and low temperatures (Fahrenheit) for various North Carolina cities.