May Weather in Charleston, United States

Last updated: June 24, 2025

In May, the average temperature in Charleston, United States hovers around 21°C (70°F), with nighttime lows dipping to 4°C (39°F) and daytime highs soaring to 33°C (92°F). Expect about 151 mm (6.0 in) of precipitation spread across 14 days, contributing to an average humidity of 82%. Whether you're exploring the outdoors or seeking shelter from the rain, prepare for a lively weather experience!

May Temperature in Charleston

In May in Charleston, the average temperature is 21°C (70°F). The maximum can reach 33°C (92°F), while the minimum can dip as low as 4°C (39°F). This weather makes Charleston an ideal destination for travelers seeking mild temperatures and a range of outdoor activities.

May Weather in Charleston: Daily Temperature Highs, Lows, and Averages

The chart illustrates May temperature patterns in Charleston, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Charleston, May typically has an average temperature of 21°C (70°F), with highs reaching up to 33°C (92°F) and lows dropping to around 4°C (39°F).

Data source: Temperature data for Charleston generated using information from the Copernicus Climate Change Service.

May Precipitation in Charleston

In Charleston in May, the precipitation amount is 151 mm (6.0 in) spread over a duration of 14 days.

May Precipitation Trends in Charleston

The chart displays monthly precipitation patterns in Charleston, with values for each month alongside May’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how May’s conditions compare to those of other months. In Charleston, May typically receives around 151 mm (6.0 inches) of precipitation spread over approximately 14 days.

Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

May Humidity in Charleston

In Charleston in May, humidity is 82%. With an average temperature of 21°C (70°F), this humidity feels like a warm, sticky embrace that can quickly lead to discomfort for travelers, making outdoor activities less enjoyable and requiring frequent breaks for hydration.

May Average Humidity in Charleston

This chart illustrates the average monthly humidity levels in Charleston, with May’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In May, average humidity in Charleston is approximately 82%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for May generated using information from the Copernicus Climate Change Service.

May UV Index in Charleston

In Charleston in May, the maximum UV index reaches 11, which corresponds to an extreme Exposure Category. With a time to burn of just 10 minutes, it's essential to take precautions. For more details, you can check the Hourly UV Index in Charleston.

Maximum UV Index Levels in Charleston for May

The chart shows the monthly maximum UV Index (UVI) for Charleston in May, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In May, the maximum UV index in Charleston typically reaches 11, which falls under the extreme exposure category.

Data source: Charleston May UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

Extreme (11+): Avoid the sun, stay in shade.
Very High (8-10): Limit sun exposure.
High (6-7): Use SPF 30+ and protective clothing.
Moderate (3-5): Midday shade recommended.
Low (0-2): No protection needed.

How May Weather in Charleston Compares to Other Months

Weather in Charleston varies notably across the year, with each month offering distinct climate conditions. This page compares May’s weather to other months in Charleston, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Charleston, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	3°C (38°F)	110 mm (4.3 inches)	86%	moderate
February Weather	5°C (41°F)	139 mm (5.5 inches)	84%	high
March Weather	10°C (51°F)	169 mm (6.6 inches)	84%	high
April Weather	14°C (58°F)	140 mm (5.5 inches)	80%	very high
May Weather	21°C (70°F)	151 mm (6.0 inches)	82%	extreme
June Weather	25°C (78°F)	112 mm (4.4 inches)	83%	extreme
July Weather	27°C (81°F)	101 mm (4.0 inches)	79%	very high
August Weather	25°C (78°F)	102 mm (4.0 inches)	76%	very high
September Weather	23°C (74°F)	85 mm (3.3 inches)	75%	very high
October Weather	16°C (62°F)	122 mm (4.8 inches)	74%	high
November Weather	8°C (47°F)	101 mm (4.0 inches)	85%	moderate
December Weather	6°C (43°F)	97 mm (3.8 inches)	88%	moderate