Climate and Average Weather Year Round in Durham North Carolina, United States

In Durham, the summers are hot and muggy, the winters are short and very cold, and it is wet and partly cloudy year round. Over the course of the year, the temperature typically varies from 32°F to 89°F and is rarely below 19°F or above 95°F.

Based on the tourism score, the best times of year to visit Durham for warm-weather activities are from early May to mid June and from mid August to mid October.

The hot season lasts for 3.6 months, from May 27 to September 15, with an average daily high temperature above 81°F. The hottest month of the year in Durham is July, with an average high of 88°F and low of 70°F.

The cool season lasts for 2.9 months, from December 1 to February 28, with an average daily high temperature below 58°F. The coldest month of the year in Durham is January, with an average low of 33°F and high of 51°F.

In Durham, the average percentage of the sky covered by clouds experiences mild seasonal variation over the course of the year.

The clearer part of the year in Durham begins around July 28 and lasts for 3.9 months, ending around November 24.

The clearest month of the year in Durham is October, during which on average the sky is clear, mostly clear, or partly cloudy 64% of the time.

The cloudier part of the year begins around November 24 and lasts for 8.1 months, ending around July 28.

The cloudiest month of the year in Durham is January, during which on average the sky is overcast or mostly cloudy 50% of the time.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Durham varies throughout the year.

The wetter season lasts 3.8 months, from May 8 to September 1, with a greater than 32% chance of a given day being a wet day. The month with the most wet days in Durham is July, with an average of 13.0 days with at least 0.04 inches of precipitation.

The drier season lasts 8.2 months, from September 1 to May 8. The month with the fewest wet days in Durham is November, with an average of 6.4 days with at least 0.04 inches of precipitation.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. The month with the most days of rain alone in Durham is July, with an average of 13.0 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 44% on July 17.

Rainfall

To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Durham experiences some seasonal variation in monthly rainfall.

Rain falls throughout the year in Durham. The month with the most rain in Durham is August, with an average rainfall of 3.8 inches.

The month with the least rain in Durham is January, with an average rainfall of 2.7 inches.

Snowfall

As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Durham experiences some seasonal variation in monthly snowfall.

The snowy period of the year lasts for 3.1 months, from December 9 to March 14, with a sliding 31-day snowfall of at least 1.0 inches. The month with the most snow in Durham is February, with an average snowfall of 3.5 inches.

The snowless period of the year lasts for 8.9 months, from March 14 to December 9. The least snow falls around July 23, with an average total accumulation of 0.0 inches.

The length of the day in Durham varies significantly over the course of the year. In 2023, the shortest day is December 21, with 9 hours, 43 minutes of daylight; the longest day is June 21, with 14 hours, 36 minutes of daylight.

The earliest sunrise is at 5:58 AM on June 13, and the latest sunrise is 1 hour, 43 minutes later at 7:40 AM on November 4. The earliest sunset is at 5:01 PM on December 5, and the latest sunset is 3 hours, 35 minutes later at 8:36 PM on June 29.

Daylight saving time (DST) is observed in Durham during 2023, starting in the spring on March 12, lasting 7.8 months, and ending in the fall on November 5.

The figure below presents a compact representation of key lunar data for 2023. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases.

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

Durham experiences extreme seasonal variation in the perceived humidity.

The muggier period of the year lasts for 4.4 months, from May 22 to October 1, during which time the comfort level is muggy, oppressive, or miserable at least 20% of the time. The month with the most muggy days in Durham is July, with 24.2 days that are muggy or worse.

The month with the fewest muggy days in Durham is February, with 0.0 days that are muggy or worse.

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed in Durham experiences mild seasonal variation over the course of the year.

The windier part of the year lasts for 6.3 months, from November 5 to May 13, with average wind speeds of more than 5.0 miles per hour. The windiest month of the year in Durham is March, with an average hourly wind speed of 6.2 miles per hour.

The calmer time of year lasts for 5.7 months, from May 13 to November 5. The calmest month of the year in Durham is August, with an average hourly wind speed of 3.9 miles per hour.

The predominant average hourly wind direction in Durham varies throughout the year.

The wind is most often from the north for 1.8 months, from January 23 to March 18; for 2.9 months, from August 30 to November 27; and for 1.1 weeks, from December 20 to December 28, with a peak percentage of 36% on October 23. The wind is most often from the west for 4.5 months, from March 18 to August 3; for 3.3 weeks, from November 27 to December 20; and for 3.7 weeks, from December 28 to January 23, with a peak percentage of 38% on July 13. The wind is most often from the south for 3.3 weeks, from August 3 to August 26, with a peak percentage of 31% on August 3.

To characterize how pleasant the weather is in Durham throughout the year, we compute two travel scores.

The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best times of year to visit Durham for general outdoor tourist activities are from early May to mid June and from mid August to mid October, with a peak score in the third week of September.

The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Durham for hot-weather activities is from mid June to early September, with a peak score in the second week of August.

Methodology

For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.

Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.

Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.

Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.

Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

The growing season in Durham typically lasts for 7.3 months (224 days), from around March 29 to around November 8, rarely starting before March 8 or after April 21, and rarely ending before October 20 or after November 29.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

Based on growing degree days alone, the first spring blooms in Durham should appear around February 17, only rarely appearing before January 30 or after March 8.

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy experiences significant seasonal variation over the course of the year.

The brighter period of the year lasts for 4.1 months, from April 16 to August 20, with an average daily incident shortwave energy per square meter above 6.0 kWh. The brightest month of the year in Durham is June, with an average of 6.8 kWh.

The darker period of the year lasts for 3.0 months, from November 9 to February 7, with an average daily incident shortwave energy per square meter below 3.3 kWh. The darkest month of the year in Durham is December, with an average of 2.5 kWh.

For the purposes of this report, the geographical coordinates of Durham are 35.994 deg latitude, -78.899 deg longitude, and 400 ft elevation.

The topography within 2 miles of Durham contains only modest variations in elevation, with a maximum elevation change of 141 feet and an average elevation above sea level of 359 feet. Within 10 miles contains only modest variations in elevation (604 feet). Within 50 miles contains significant variations in elevation (958 feet).

The area within 2 miles of Durham is covered by artificial surfaces (94%), within 10 miles by trees (58%) and artificial surfaces (36%), and within 50 miles by trees (61%) and cropland (27%).