Hottest (avg)
#5 / 12
Sits around the middle of the year.
May in context
How it compares to the rest of the year in Charleston.
Wettest (avg)
#11 / 12
One of the drier months.
Daylight Hours
#3 / 12
Long daylight hours.
Windiest (avg)
#5 / 12
Close to the yearly wind average.
Highest UV
#3 / 12
UV runs high compared with most months.
Most Humid
#9 / 12
Humidity stays close to the yearly norm.
Monthly climate breakdown
A detailed look at the typical climate conditions for May.
Thermal profile
Temperature
Typical daytime high
- Nighttime low
-
- Feels like (avg)
-
Light window
Sunshine
13.9 h
Average daylight
- UV index (max)
- 8
- Typical sun hours
- 05:20 - 19:11
Wet-day pattern
Rain & Snow
Typical rainfall
- Rainy days
- 12 days
- Cloud cover (avg)
- 49%
Air feel
Humidity & Wind
74%
Average humidity
- Wind (avg)
-
- Wind (max gusts)
-
Historical daily baseline
Daily climate explorer
Pick a day to inspect the usual conditions through May in Charleston. Based on a 30-year historical climate baseline, not a forecast.
Primary control
Select a day
Scroll to compare daily conditions. The summary updates with your selection.
Secondary context
Monthly trend
Median daytime highs across the month, with a softer low line.
Median temperatureMedian lowTypical range
Day 15 selected for May. Temperature 25.6°C.
Historical disruption baseline
Typical disruptions in May
Based on 30 years of historical data, these are the disruption patterns most likely to affect plans in May.
Humidity High impact
Muggy days Measures: Muggy days (dew point >=20C). Observed about 29% of days (9.1 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
9.1 days / month
- Share of days
- ~29% of days
- Upper edge
- Up to ~22°C (P95)
Why this matters
Muggy conditions are possible on ~9 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Heat High impact
Hot feels-like days Measures: Hot feels-like days (>=32C). Observed about 18% of days (5.7 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
5.7 days / month
- Share of days
- ~18% of days
- Upper edge
- Up to ~37°C (P95)
Why this matters
Feels-like heat >=32C is possible on ~6 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Rain High impact
Rain disruption Measures: Likely rain disruption days. Observed about 12% of days (3.9 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
3.9 days / month
- Share of days
- ~12% of days
- Upper edge
- Up to ~31mm (P95)
Why this matters
Rain disruption risk appears on ~4 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Rain High impact
Washout risk Measures: Washout day risk. Observed about 11% of days (3.3 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
3.3 days / month
- Share of days
- ~11% of days
- Upper edge
- Up to ~32mm (P95)
Why this matters
Washout conditions are possible on ~3 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Heat High impact
Very hot feels-like Measures: Very hot feels-like days (>=35C). Observed about 4% of days (1.2 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.2 days / month
- Share of days
- ~4% of days
- Upper edge
- Up to ~38°C (P95)
Why this matters
Very hot feels-like conditions are possible on ~1 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Wind High impact
Stormy conditions Measures: Storm-impact proxy days. Observed about 3% of days (1.1 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.1 days / month
- Share of days
- ~3% of days
- Upper edge
- Up to ~78km/h (P95)
Why this matters
Stormy conditions are possible on ~1 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Show all disruptions (23 more)
Rain High impact
Heavy rain days Measures: Heavy rain days (>=10mm). Observed about 7% of days (2.1 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
2.1 days / month
- Share of days
- ~7% of days
- Upper edge
- Up to ~37mm (P95)
Why this matters
Heavy rain is possible on ~2 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Wind High impact
Strong gusts Measures: Strong gust days (>=60 km/h). Observed about 3% of days (0.8 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.8 days / month
- Share of days
- ~3% of days
- Upper edge
- Up to ~79km/h (P95)
Why this matters
Strong gusts are possible on ~1 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Rain High impact
Washout run Measures: Multi-day washout runs. Observed about 0.7 days/month in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.7 days / month
- Share of days
- —
- Upper edge
- Up to ~44mm (P95)
Why this matters
Multi-day washout runs are possible on ~1 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Rain High impact
Very heavy rain Measures: Very heavy rain days (>=25mm). Observed about 2% of days (0.5 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.5 days / month
- Share of days
- ~2% of days
- Upper edge
- Up to ~48mm (P95)
Why this matters
Very heavy rain is possible on ~0 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Heat Moderate
Hot days Measures: Hot days (>=30C). Observed about 8% of days (2.5 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
2.5 days / month
- Share of days
- ~8% of days
- Upper edge
- Up to ~34°C (P95)
Why this matters
Hot days are possible on ~2 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Heat Moderate
Heat stress risk Measures: High heat stress days. Observed about 4% of days (1.2 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.2 days / month
- Share of days
- ~4% of days
- Upper edge
- Up to ~38°C (P95)
Why this matters
Heat stress is possible on ~1 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Humidity Minor
Humid days Measures: Humid days (dew point >=18C). Observed about 54% of days (16.7 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
16.7 days / month
- Share of days
- ~54% of days
- Upper edge
- Up to ~22°C (P95)
Why this matters
Humid conditions are possible on ~17 days. Comfort and pace can drop quickly, so plan shorter outdoor blocks with air-conditioned backup stops.
Wind Minor
Gusty days Measures: Gusty days (>=40 km/h). Observed about 48% of days (14.8 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
14.8 days / month
- Share of days
- ~48% of days
- Upper edge
- Up to ~61km/h (P95)
Why this matters
Gusty conditions are possible on ~15 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Rain Minor
Wet days Measures: Wet days (>=0.1mm). Observed about 48% of days (14.8 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
14.8 days / month
- Share of days
- ~48% of days
- Upper edge
- Up to ~19mm (P95)
Why this matters
Measurable rain is possible on ~15 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Cloud Minor
Cloudy days Measures: Cloudy days (cloud cover >=60%). Observed about 38% of days (11.8 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
11.8 days / month
- Share of days
- ~38% of days
- Upper edge
- Up to ~99% (P95)
Why this matters
Cloudy skies are possible on ~12 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Rain Minor
Rainy hours Measures: Rain-hours signal (>=3h rain). Observed about 33% of days (10.1 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
10.1 days / month
- Share of days
- ~33% of days
- Upper edge
- Up to ~16h (P95)
Why this matters
Several rainy hours are possible on ~10 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Humidity Minor
High humidity Measures: High humidity days (RH >=80%). Observed about 30% of days (9.4 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
9.4 days / month
- Share of days
- ~30% of days
- Upper edge
- Up to ~90% (P95)
Why this matters
High humidity is possible on ~9 days. Comfort and pace can drop quickly, so plan shorter outdoor blocks with air-conditioned backup stops.
Rain Minor
Wet most of day Measures: Wet-most-of-day signal (>=6h rain). Observed about 20% of days (6.1 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
6.1 days / month
- Share of days
- ~20% of days
- Upper edge
- Up to ~19h (P95)
Why this matters
Wet-most-of-day conditions are possible on ~6 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Cloud Minor
Mostly cloudy days Measures: Mostly cloudy days (cloud cover >=80%). Observed about 19% of days (6.0 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
6.0 days / month
- Share of days
- ~19% of days
- Upper edge
- Up to ~100% (P95)
Why this matters
Mostly cloudy skies are possible on ~6 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Heat Minor
Warm nights Measures: Warm nights (min >=22C). Observed about 19% of days (5.9 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
5.9 days / month
- Share of days
- ~19% of days
- Upper edge
- Up to ~25°C (P95)
Why this matters
Warm nights are possible on ~6 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Humidity Minor
Convective risk Measures: Convective storm risk proxy. Observed about 10% of days (3.1 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
3.1 days / month
- Share of days
- ~10% of days
- Upper edge
- Up to ~22°C (P95)
Why this matters
Convective risk signal appears on ~3 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Cloud Minor
Overcast days Measures: Overcast days (cloud cover >=95%). Observed about 7% of days (2.1 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
2.1 days / month
- Share of days
- ~7% of days
- Upper edge
- Up to ~100% (P95)
Why this matters
Overcast skies are possible on ~2 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Heat Minor
Feels-like heatwave Measures: Feels-like heatwave runs (>=3 days). Observed about 0.6 days/month in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.6 days / month
- Share of days
- —
- Upper edge
- Up to ~37°C (P95)
Why this matters
Feels-like heatwave runs are possible on ~1 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Wind Minor
Breezy days Measures: Breezy days (mean wind >=25 km/h). Observed about 2% of days (0.5 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.5 days / month
- Share of days
- ~2% of days
- Upper edge
- Up to ~33km/h (P95)
Why this matters
Breezy conditions are possible on ~1 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Visibility Minor
Fog-likely signal Measures: Fog-likely visibility proxy. Observed about 1% of days (0.4 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.4 days / month
- Share of days
- ~1% of days
- Upper edge
- Up to ~92% (P95)
Why this matters
Fog-likely conditions are possible on ~0 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Other Minor
Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data Measures: Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data. Observed about 1% of days (0.4 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.4 days / month
- Share of days
- ~1% of days
- Upper edge
- Up to ~92 (P95)
Why this matters
Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data is possible on ~0 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Heat Minor
Hot nights Measures: Hot nights (min >=25C). Observed about 1% of days (0.2 days/month) in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.2 days / month
- Share of days
- ~1% of days
- Upper edge
- Up to ~26°C (P95)
Why this matters
Hot nights are possible on ~0 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Heat Minor
Heatwave run Measures: Heatwave runs (>=3 hot days). Observed about 0.1 days/month in May. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.1 days / month
- Share of days
- —
- Upper edge
- Up to ~34°C (P95)
Why this matters
Heatwave runs are possible on ~0 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Travel planning FAQ
Frequently asked questions
Quick answers to the weather questions you ask the most.
Is May a good time to visit Charleston?
Typical May days in Charleston reach highs of 26°C (79°F) with nights around 19°C (66°F). It usually feels warm by day and mild after dark. It is one of the drier months, which suits outdoor exploring and sightseeing.
What are temperatures like in May?
In May, you can usually expect highs of 26°C (79°F) and lows near 19°C (66°F). That means warm days and mild nights, so pack layers you can add or remove.
How much does it rain in May?
Rainfall in May averages 68 mm (2.7 in) across roughly 12 days. Overall it is a quite rainy time of year, so a light rain jacket and waterproof shoes are very handy.
How many hours of daylight are there in May?
You can expect about 14 hours of daylight in May. Sunrise is typically around 05:20 and sunset near 19:11. You get long days with comfortable amounts of daylight.
How strong is the sun in May?
UV levels frequently reach very high levels (around 8), so strong sun protection is essential, especially around midday.
Is it windy in May?
In May, average wind speeds are around 14 km/h (9 mph), with gusts on the windiest days reaching about 52 km/h (32 mph). On the ground, it is it can feel quite windy at times, particularly when weather systems move through.