North Carolina Has The Privilege Of Enjoying All Four Seasons Without Major Weather Extremes.
TEMPERATURE - The most important single influence contributing to the variability of North Carolina climate is altitude. In all seasons of the year, the average temperature varies more than 20° Fahrenheit from the lower coast to the highest elevations. The average annual temperature at Southport on the lower coast is nearly as high as that of interior northern Florida, while the average on the summit of Mount Mitchell is lower than that of Buffalo, NY.
In winter, the greater part of North Carolina is partially protected by the mountain ranges from the frequent outbreaks of cold air which move southeastward across the central States. Such outbreaks often move southward all the way to the Gulf of Mexico without attaining sufficient strength and depth to traverse the heights of the Appalachian Range. When cold waves do break across, they are usually modified by the crossing and the descent on the eastern slopes. The temperature drops to 10° or 12° F about once during an average winter over central North Carolina, ranging some 10° F warmer the coast and 10° F colder in the upper mountains. Temperatures as low as 0° F are rare outside the mountains, but have occurred throughout the western part of the State. The lowest temperature of record is minus 34° F recorded January 21, 1985, at Mount Mitchell. Winter temperatures in the eastern sections are modified by the Atlantic Ocean which raises the average winter temperature and decreases the average day-to-night range.
In spring, the storm systems that bring cold weather southward reach North Carolina less often and less forcefully, and temperatures begin to modify. The rise in average temperatures is greater in May than in any other month.
Occasional invasions of cool dry air from the north continue during the summer, but their effect on temperatures is slight and of short duration.
The increase in sunshine which follows usually brings temperatures back up quickly. When the dryness of the air is sufficient to keep cloudiness at a minimum for several days, temperatures may occasionally reach 100° F or higher in the interior at elevations below 1,500 feet. Ordinarily, however, summer cloudiness develops to limit the sun's heating while temperatures are still in the 90-degree range. An entire summer sometimes passes without a high of 100° F being recorded in the State. The average daily maximum reading in midsummer is below 90° F for most localities.
Differences in temperatures over the various parts of the State are no less pronounced in summer than in winter. The warmest days are found in the interior rather than near the coast in summer. The average daily maximum temperature at midsummer exceeds 92° F at Goldsboro and Fayetteville, for example, while on the southernmost part of the coast during the same season it is only 89° F. The mid-July average afternoon high temperature atop Mount Mitchell is only 68° F, while over widely populated areas in the Mountain Division the figure is around 80° F. Morning temperatures average about 20 degrees lower than those in the afternoon except along the immediate coast, where the daily range is only 10 to 15 degrees.
Autumn is the season of most rapidly changing temperature, the daily downward trend being greater than the corresponding rise in spring. The drop-off is greatest during October, and continues at a rapid pace in November, so that average daily temperatures by the end of that month are within about five degrees of the lowest point of the year.
PRECIPITATION - While there are no distinct wet and dry seasons in North Carolina, average rainfall does vary around the year. Summer precipitation is normally the greatest, and July is the wettest month. Summer rainfall is also the most variable, occurring mostly in connection with showers and thunderstorms. Daily showers are not uncommon, nor are periods of one to two weeks without rain. Autumn is the driest season, and November the driest month. Precipitation during winter and spring occurs mostly in connection with migratory low pressure storms, which appear with greater regularity and in a more even distribution than summer showers. In southwestern North Carolina, where moist southerly winds are forced upward in passing over the mountain barrier, the annual average is more than 90 inches. This region is the rainiest in the eastern United States. Less than 50 miles to the north, in the valley of the French Broad River, sheltered by mountain ranges on all sides, is the driest point south of Virginia and east of the Mississippi River. Here the average annual precipitation is only 37 inches. East of the Mountains, average annual rainfall ranges mostly between 40 and 55 inches.
Winter-type precipitation usually occurs with southerly through easterly winds, and is seldom associated with very cold weather. Snow and sleet occur on an average once or twice a year near the coast, and not much more often over the southeastern half of the State. Such occurrences are nearly always connected with northeasterly winds, generated when a high pressure system over the interior, or northeastern United States, causes a southward flow of cold dry air down the coastline, while offshore a low pressure system brings in warmer, moist air from the North Atlantic. Farther inland, over the Mountains and western Piedmont, frozen precipitation sometimes occurs in connection with low pressure storms, and in the extreme west with cold front passages from the northwest. Average winter snowfall over the State ranges from about inch per year on the outer banks and along the lower coast to about 10 inches in the northern Piedmont and 16 inches in the southern Mountains. Some of the higher mountain peaks and upper slopes receive an average of nearly 50 inches a year.
OTHER CLIMATIC FACTORS - The average relative humidity does not vary greatly from season to season but is generally the highest in winter and lowest in spring. The lowest relative humidities are found over the southern Piedmont, where the year around average is about 65 percent. The highest are along the immediate coast, averaging around 75 percent. The least amount of actual moisture is found in the higher mountain areas, but the lower temperatures there result in relative humidities that are about the same as elsewhere in the State.
Sunshine is relatively abundant, the average annual percent of possible sunshine ranges from 58 to 65 at the various stations having sunshine recorders. An average of 126 days per year are clear, 117 partly cloudy, and 122 cloudy, while measurable rain falls on 120 days. The prevailing winds are generally from the southwest for 10 months of the year, and from the northeast during September and October. The average wind speed is about eight to 10 miles per hour, however, winds along the coast can exceed 100 miles per hour when hurricanes strike.
Raleigh Area Forecast
http://www.weather.com/weather/tenday/USNC0558?from=search_10day
- NUMBER1EXPERT™ 
