Average Weather in Charleston South Carolina, United States
In Charleston, the summers are hot and oppressive, the winters are cold and windy, and it is wet and partly cloudy year round. Over the course of the year, the temperature typically varies from 43°F to 89°F and is rarely below 30°F or above 94°F.
The hot season lasts for 3.7 months, from May 27 to September 18, with an average daily high temperature above 83°F. The hottest day of the year is July 23, with an average high of 89°F and low of 77°F.
The cool season lasts for 3.0 months, from December 1 to March 2, with an average daily high temperature below 65°F. The coldest day of the year is January 17, with an average low of 43°F and high of 59°F.
Average High and Low Temperature
The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.
Average Hourly Temperature
In Charleston, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.
The clearer part of the year in Charleston begins around September 12 and lasts for 3.1 months, ending around December 16. On October 27, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 66% of the time, and overcast or mostly cloudy 34% of the time.
The cloudier part of the year begins around December 16 and lasts for 8.9 months, ending around September 12. On July 27, the cloudiest day of the year, the sky is overcast or mostly cloudy 57% of the time, and clear, mostly clear, or partly cloudy 43% 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 Charleston varies significantly throughout the year.
The wetter season lasts 3.4 months, from June 4 to September 17, with a greater than 35% chance of a given day being a wet day. The chance of a wet day peaks at 51% on July 30.
The drier season lasts 8.6 months, from September 17 to June 4. The smallest chance of a wet day is 19% on October 30.
Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 51% on July 30.
Daily Chance of Precipitation
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. Charleston experiences significant seasonal variation in monthly rainfall.
Rain falls throughout the year in Charleston. The most rain falls during the 31 days centered around August 19, with an average total accumulation of 5.2 inches.
The least rain falls around November 11, with an average total accumulation of 2.3 inches.
Average Monthly Rainfall
The length of the day in Charleston varies significantly over the course of the year. In 2017, the shortest day is December 21, with 9 hours, 60 minutes of daylight; the longest day is June 21, with 14 hours, 19 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 6:11 AM on June 11, and the latest sunrise is 1 hour, 29 minutes later at 7:40 AM on November 4. The earliest sunset is at 5:13 PM on December 4, and the latest sunset is 3 hours, 19 minutes later at 8:31 PM on June 29.
Daylight saving time (DST) is observed in Charleston during 2017, starting in the spring on March 12, lasting 7.8 months, and ending in the fall on November 5.
Sunrise & Sunset with Twilight and Daylight Saving Time
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.
Charleston experiences extreme seasonal variation in the perceived humidity.
The muggier period of the year lasts for 6.0 months, from April 26 to October 27, during which time the comfort level is muggy, oppressive, or miserable at least 26% of the time. The muggiest day of the year is July 22, with muggy conditions 99% of the time.
The least muggy day of the year is January 31, with muggy conditions 2% of the time.
Humidity Comfort Levels
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 Charleston experiences mild seasonal variation over the course of the year.
The windier part of the year lasts for 6.3 months, from October 26 to May 3, with average wind speeds of more than 5.0 miles per hour. The windiest day of the year is February 26, with an average hourly wind speed of 5.9 miles per hour.
The calmer time of year lasts for 5.7 months, from May 3 to October 26. The calmest day of the year is August 17, with an average hourly wind speed of 4.2 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Charleston varies throughout the year.
The wind is most often from the west for 2.3 months, from January 7 to March 17, with a peak percentage of 36% on January 20. The wind is most often from the south for 5.3 months, from March 17 to August 26, with a peak percentage of 53% on July 19. The wind is most often from the north for 3.1 months, from October 5 to January 7, with a peak percentage of 36% on January 1.
Charleston is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.
The average water temperature experiences some seasonal variation over the course of the year.
The time of year with warmer water lasts for 3.5 months, from June 14 to September 28, with an average temperature above 79°F. The day of the year with the warmest water is August 3, with an average temperature of 83°F.
The time of year with cooler water lasts for 4.1 months, from December 19 to April 21, with an average temperature below 67°F. The day of the year with the coolest water is March 6, with an average temperature of 63°F.
Average Water Temperature
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 2.9 months, from April 6 to July 2, with an average daily incident shortwave energy per square meter above 5.9 kWh. The brightest day of the year is May 14, with an average of 6.7 kWh.
The darker period of the year lasts for 2.9 months, from November 10 to February 6, with an average daily incident shortwave energy per square meter below 3.6 kWh. The darkest day of the year is December 21, with an average of 2.8 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Charleston are 32.777 deg latitude, -79.931 deg longitude, and 3 ft elevation.
The topography within 2 miles of Charleston is essentially flat, with a maximum elevation change of 26 feet and an average elevation above sea level of 4 feet. Within 10 miles is also essentially flat (66 feet). Within 50 miles is essentially flat (509 feet).
The area within 2 miles of Charleston is covered by water (60%), artificial surfaces (27%), and herbaceous vegetation (12%), within 10 miles by artificial surfaces (33%) and water (33%), and within 50 miles by water (50%) and trees (27%).
This report illustrates the typical weather in Charleston, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Temperature and Dew Point
There are 2 weather stations near enough to contribute to our estimation of the temperature and dew point in Charleston.
For each station, the records are corrected for the elevation difference between that station and Charleston according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
The estimated value at Charleston is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Charleston and a given station.
The stations contributing to this reconstruction are: Charleston NAS (60%, 8 kilometers, north) and Charleston Executive Airport (40%, 11 kilometers, southwest).
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , by Jean Meeus.
All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.
Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.
Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.
Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .
Time zones for aiports and weather stations are provided by AskGeo.com .
Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.