Charleston weather in May

In May, Charleston sees average daytime highs of 74°F and overnight lows near 56°F, with 4.7 in of rain across 12.7 wet days and about 14.1 hours of daylight. It is the 5th-warmest and 2nd-wettest month of the year here.

Highs climb over the month, from about 69°F in the first days to 77°F by the end. The sky is clear or mostly clear about 25% of the time in May, and the air most often feels dry.

Daylight stretches from about 13 h 36 min at the start of May to 14 h 36 min by month's end. Set against the rest of the year, May is Charleston's 8th-clearest and 8th-windiest month. For the whole year in context, see Charleston's year-round climate.

Daytime high
74°
5th warmest
Overnight low
56°
8th coldest
Rainfall
4.7 in
12.7 wet days
Daylight
14 h 12 min
4:44 AM – 6:54 PM
Cloud cover
64%
8th clearest
Wind
8 mph
8th windiest
Solar energy
5.79 kWh/m²
Travel score
6.3
out of 10

Charleston is city in and the county seat of Coles County, Illinois, United States.

Density
876/km²
people per km²
Founded
1831

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in May

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 69°F in the first days to 77°F by the end.

A typical May day in Charleston reaches about 74°F in the afternoon and slips back to 56°F overnight — a 18°F spread between the day's warmth and the night's chill. On most days the high lands between 61°F and 85°F. Set against its neighbours, May runs about 10°F warmer than April and about 8°F cooler than June.

40°60°80°151015202531
Avg high (°F)Avg low (°F)
16950
26951
36951
47051
57052
67152
77153
87153
97253
107254
117254
127354
137355
147355
157355
167455
177456
187456
197456
207557
217557
227557
237658
247658
257658
267759
277759
287760
297860
307860
317861

How May really feels in Charleston

Once humidity and wind are folded in, May averages 0 days that feel above 90°F and 0 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F
0
heat index over the day's high
Days feeling ≤ 32°F
0
wind chill below the day's low

May sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Charleston weather by month

How May compares with the rest of the year at a glance. May is the 5th-warmest and 2nd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan37° / 22°3.08.93.89.50.0
Feb41° / 25°2.57.83.410.40.3
Mar52° / 34°3.410.51.611.72.7
Apr64° / 45°4.811.80.3135.4
May74° / 56°4.712.7014.16.3
Jun82° / 65°4.211.2014.75.9
Jul85° / 68°3.710.7014.55.4
Aug83° / 65°3.08.5013.66.0
Sep78° / 58°2.97.2012.37.3
Oct65° / 46°3.38.20.1116.2
Nov52° / 36°3.58.30.79.82.8
Dec41° / 27°2.78.92.99.30.2

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 25% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 15% of May, with mostly cloudy or overcast conditions the remaining 59%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14060
24060
34258
44159
54159
64159
74060
84159
94159
104159
114159
124159
134159
144159
154159
164159
174159
184060
194060
204060
213961
223961
233961
244060
254060
263961
274060
284159
294159
304258
314357

Chance of precipitation in May

Any precipitation

Charleston gets around 4.7 in of rain over 12.7 wet days in May. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 41% and peaks near 44% on the wettest days.

0%10%20%30%40%50%151015202531
Rain chance (%)
144
243
343
443
543
642
742
842
942
1041
1141
1241
1341
1441
1541
1641
1741
1841
1941
2041
2141
2240
2340
2440
2540
2640
2740
2839
2939
3039
3138

Humidity in May

DryComfortableHumidMuggyOppressiveMiserable

Most of May feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, May lands in the dry band about 55% of days. Sticky, muggy-or-worse air turns up on roughly 10% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
17714810
27515820
37316920
471171020
568181130
667181230
765191240
864191340
963191350
1062191450
1160191560
1260191560
1358191670
1458191670
1556191780
1655191790
1754191890
18541818100
19521819110
20511819120
21501820130
22481821130
23471821140
24451821151
25441822161
26431822161
27421822171
28411922181
29401922181
30381923191
31371923201

Wind in May

Winds average 8 mph in May.

Across May, daily wind ranges from about 8 mph on the calmest days to 9 mph at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (mph)Feels
19light breeze
29light breeze
39light breeze
49light breeze
59light breeze
69light breeze
79light breeze
89light breeze
99light breeze
109light breeze
119light breeze
129light breeze
138light breeze
148light breeze
158light breeze
168light breeze
178light breeze
188light breeze
198light breeze
208light breeze
218light breeze
228light breeze
238light breeze
248light breeze
258light breeze
268light breeze
278light breeze
288light breeze
298light breeze
308light breeze
318light breeze

Sunrise & sunset in May

DaylightNight

Daylight runs from about 13 h 36 min at the start of May to 14 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 60 minutes over May. Sunrise moves from 5:01 AM to 4:33 AM, and sunset from 6:39 PM to 7:07 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.65:016:39
213.74:596:40
313.74:586:41
413.84:576:42
513.84:566:43
613.84:556:44
713.94:536:45
813.94:526:46
913.94:516:47
1014.04:506:48
1114.04:496:49
1214.04:486:50
1314.14:476:51
1414.14:466:52
1514.14:456:53
1614.24:446:54
1714.24:436:55
1814.24:426:56
1914.34:416:57
2014.34:416:58
2114.34:406:58
2214.34:396:59
2314.44:387:00
2414.44:387:01
2514.44:377:02
2614.44:367:03
2714.54:367:04
2814.54:357:04
2914.54:357:05
3014.54:347:06
3114.64:337:07

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.79 kWh/m².

For context, solar energy here swings from a low near 1.79 kWh/m² to a high of 6.44 kWh/m² in June across the year — May's 5.79 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.4Bright
25.4Bright
35.4Bright
45.5Bright
55.5Bright
65.5Bright
75.6Bright
85.6Bright
95.6Bright
105.7Bright
115.7Bright
125.7Bright
135.7Bright
145.8Bright
155.8Bright
165.8Bright
175.8Bright
185.9Bright
195.9Bright
205.9Bright
215.9Bright
226.0Bright
236.0Bright
246.0Bright
256.0Intense
266.0Intense
276.0Intense
286.1Intense
296.1Intense
306.1Intense
316.1Intense
Planning a trip in May

Is May a good time to visit Charleston?

Our two travel scores rate May for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

6.3
Sightseeing
2nd-best month of the year
4.9
Beach & pool
5th-best month of the year

May is a reasonable time to visit Charleston for sightseeing.

What to pack for Charleston in May

From May's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In May, Charleston sees daytime highs around 74°F and nights near 56°F. Worth packing: light clothes, rain gear and sun protection. About 13 days see rain.

light clothesrain gearsun protection

UV index in Charleston in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 8 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Charleston peaks around July 10 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 23 at about 2 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 9 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateJul 10UV 9Dec 23UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May8Very high
Jun9Very high
Jul9Very high
Aug8Very high
Sep6High
Oct4Moderate
Nov3Moderate
Dec2Low

Air quality in Charleston in May

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where May falls, not just the annual average.

Air quality in Charleston is worst in July — around 16 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (October, 8 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateModerateGoodJul 1616 µg/m³Oct 218 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb13Moderate
Mar13Moderate
Apr11Good
May14Moderate
Jun15Moderate
Jul16Moderate
Aug14Moderate
Sep11Good
Oct8Good
Nov8Good
Dec9Good
Location & terrain

Where is Charleston?

Charleston sits at 39.5°N, 88.2°W, 669 ft above sea level, in United States. The nearest listed city is Mattoon, 11 mi away.

Topography around Charleston

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Charleston.

Within 2 miles, the terrain around Charleston has only modest variations in elevation — a maximum elevation change of 187 ft around an average of 676 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 282 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 456 ft.

The land around Charleston is covered by cropland (38%) and trees (32%) within 2 miles, cropland (68%) and trees (23%) within 10 miles, and cropland (74%) and trees (21%) within 50 miles.

2 miles
187 ft
10 miles
282 ft
50 miles
456 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
May weather nearby: Mattoon 11 mi · Terre Haute 41 mi · Urbana 42 mi · Champaign 43 mi · Decatur 48 mi · Danville 52 mi · Vincennes 66 mi · Crawfordsville 79 mi

United States travel facts

Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 100% of US
price level, 2025
GDP per capita
$90,027
2025
Happiness
6.8 / 10
World Happiness, 2025
Safe drinking water
98%
of population, 2024
Homicide rate
5.8
per 100k, 2023
Road deaths
12.7
per 100k/yr, 2019
Income group
High
World Bank
Religion
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Charleston (39.4962°, -88.1762°, elevation 669 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).