May weather forecastCharleston, SC

Trees along both sides of a street in Charleston, South Carolina

May

Weather in May

May nudges Charleston into the noisy, chaotic season of summer. As temperatures inch higher, residents brace for longer, sunnier days. Amidst these warming trends, the interesting facet of May's weather is the significantly high rainfall of 2.87" (73mm) that the city receives. The sea begins to warm up, becoming agreeable for water sports and other activities.

Temperature

In Charleston, the average high-temperature in May slightly rises, from a pleasant 72.7°F (22.6°C) in April, to a warm 79.5°F (26.4°C). Charleston reports a consistent average low-temperature of 68.2°F (20.1°C) throughout May nights.

Humidity

In May, the average relative humidity in Charleston is 75%.

Rainfall

In Charleston, South Carolina, during May, the rain falls for 15.8 days and regularly aggregates up to 2.87" (73mm) of precipitation. Throughout the year, in Charleston, there are 178.9 rainfall days, and 41.93" (1065mm) of precipitation is accumulated.

Snowfall

February through November are months without snowfall.

Ocean temperature

In Charleston, the average seawater temperature in May is 73°F (22.8°C).
Note: For those not fond of cold temperatures, taking a swim at 73°F (22.8°C) may require consideration of the sunshine, wind, and ambient temperature. While wetsuits are not mandatory, they can enhance the experience.

Daylight

The average length of the day in May in Charleston, South Carolina, is 13h and 52min.
On the first day of the month, sunrise is at 6:31 am and sunset at 8:01 pm. On the last day of May, sunrise is at 6:12 am and sunset at 8:22 pm EDT.

Sunshine

In Charleston, the average sunshine in May is 10.5h.

UV index

May through August, with an average maximum UV index of 7, are months with the highest UV index. A UV Index reading of 6 to 7 represents a high health vulnerability from unsafe exposure to UV radiation for the ordinary person.
Note: In May, the maximum UV index of 7 transforms into these recommendations:
Resist extreme sun exposure. Guarding against solar damage is essential. It's important to stay in the shade and limit exposure to the sun from 10 a.m. to 4 p.m., when UV radiation is most intense, although remember that shade structures may not provide full sun protection. A wide-brimmed hat is a shield, deflecting up to 50% of harmful UV radiation from eyes. Heads up! Sand and water reflection magnifies the UV exposure from the Sun.

Updated: Feb 13, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

In Charleston, in May, the average high-temperature is 79.5°F (26.4°C), and the average low-temperature is 68.2°F (20.1°C).

The average relative humidity in May is 75%.

In Charleston, South Carolina, in May, it is raining for 15.8 days, with typically 2.87" (73mm) of accumulated precipitation.

February through November are months without snowfall.

In Charleston, the average seawater temperature in May is 73°F (22.8°C). A person's cold intolerance, with sunshine, wind, and air temperature, are essential factors for enjoying swimming in 73°F (22.8°C) water.

In May, the average day length is 13h and 52min.

In May, on the first day of the month, sunrise is at 6:31 am and sunset at 8:01 pm. On the last day of the month, in Charleston, sunrise is at 6:12 am and sunset at 8:22 pm EDT.

The average sunshine duration in May in Charleston, South Carolina, is 10.5h.

The months with the highest UV index in Charleston are May through August, with an average maximum UV index of 7.

The average daily maximum UV index in May in Charleston is 7. A UV Index estimate of 6 to 7 represents a high health threat from unsafe exposure to Sun's UV rays.

Today

Tomorrow

Long-term

Year J F M A May J J A S O N D

Apr

May

Jun

Average high temperature

72.7°F

79.5°F

85.8°F

Average low temperature

Average pressure

Average wind speed

Average max. wind speed

10.1mph

9.2mph

8.6mph

Average wind speed gusts

Average humidity

Average rainfall

Average rainfall days

12.8

15.8

20.5

Average snowfall

Average snowfall days

Average sea temperature

Average daylight

Average sunshine

Average sunshine days

15.8

13.3

6.7

Average UV index

Average cloud cover

Average visibility

Average temperature in May
Charleston, SC

Average high temperature in May: 79.5°F

The warmest month (with the highest average high temperature) is July (88.2°F).
The month with the lowest average high temperature is January (57°F).

Average low temperature in May: 68.2°F

The month with the highest average low temperature is July (77.4°F).
The coldest month (with the lowest average low temperature) is January (44.4°F).

Average pressure in May
Charleston, SC

Average pressure in May: 30.03"Hg

The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.98"Hg).

Average wind speed in May
Charleston, SC

Average wind speed in May: 8.6mph

The windiest month (with the highest average wind speed) is April (9.4mph).
The calmest month (with the lowest average wind speed) is August (7.5mph).

Average humidity in May
Charleston, SC

Average humidity in May: 75%

The month with the highest relative humidity is December (78%).
The months with the lowest relative humidity are January and March (73%).

Average rainfall in May
Charleston, SC

Average rainfall in May: 2.87"

The wettest month (with the highest rainfall) is August (7.13").
The driest month (with the least rainfall) is January (1.42").

Average rainfall days in May
Charleston, SC

Average rainfall days in May: 15.8 days

The month with the highest number of rainy days is August (24.8 days).
The month with the least rainy days is November (8.7 days).

Average snowfall in May
Charleston, SC

Average snowfall in May: 0"

The month with the highest snowfall is January (0.12").
The months with the least snowfall are February, March, April, May, June, July, August, September, October and November (0").

Average snowfall days in May
Charleston, SC

Average snowfall days in May: 0 days

The month with the highest number of snowfall days is January (0.4 days).
The months with the least snowfall days are March, April, May, June, July, August, September, October and November (0 days).

Average sea temperature in May
Charleston, SC

Average sea temperature in May: 73°F

The best month for swimming (with the highest average sea temperature) is August (83.5°F).
The coldest month (with the lowest average sea temperature) is February (61.9°F).

Average daylight in May /
Average sunshine in May
Charleston, SC

Average daylight in May: 13h and 54min

The month with the longest days is June (Average daylight: 14h and 18min).
The month with the shortest days is December (Average daylight: 10h and 0min).

Average sunshine in May: 10h and 30min

The month with the most sunshine is July (Average sunshine: 11h and 0min).
The month with the least sunshine is December (Average sunshine: 5h and 42min).

Average sunshine days in May
Charleston, SC

Average sunshine days in May: 13.3 days

The month with the most sunshine days is January (19.3 days).
The month with the least sunshine days is August (3.8 days).

Average UV index in May
Charleston, SC

Average UV index in May: 7

The months with the highest UV index are May, June, July and August (UV index 7).
The month with the lowest UV index is January (UV index 3).

Average cloud cover in May
Charleston, SC

Average cloud cover in May: 27

The months with the most cloud cover are February and December (Cloud cover 39).
The months with the least cloud cover are June and July (Cloud cover 26).

Average visibility in May
Charleston, SC

Average visibility in May: 6mi

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).