Marion weather in May

In May, Marion sees average daytime highs of 76°F and overnight lows near 60°F, with 4.6 in of rain across 12.6 wet days and about 14 hours of daylight. It is the 5th-warmest and 2nd-wettest month of the year here.

Highs climb over the month, from about 73°F in the first days to 80°F by the end. The sky is clear or mostly clear about 26% of the time in May, and the air most often feels dry.

Daylight stretches from about 13 h 30 min at the start of May to 14 h 24 min by month's end. Set against the rest of the year, May is Marion's 9th-clearest and 8th-windiest month. For the whole year in context, see Marion's year-round climate.

Daytime high
76°
5th warmest
Overnight low
60°
8th coldest
Rainfall
4.6 in
12.6 wet days
Daylight
14 hours
4:51 AM – 6:53 PM
Cloud cover
62%
9th clearest
Wind
7 mph
8th windiest
Solar energy
5.84 kWh/m²
Travel score
6.3
out of 10

Marion is city in and the county seat of Williamson County, Illinois, United States.

Density
412/km²
people per km²
Founded
1839

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 73°F in the first days to 80°F by the end.

A typical May day in Marion reaches about 76°F in the afternoon and slips back to 60°F overnight — a 17°F spread between the day's warmth and the night's chill. On most days the high lands between 65°F and 86°F. Set against its neighbours, May runs about 9°F warmer than April and about 8°F cooler than June.

40°60°80°151015202531
Avg high (°F)Avg low (°F)
17254
27255
37355
47355
57356
67456
77457
87457
97457
107558
117558
127558
137659
147659
157659
167660
177760
187760
197760
207861
217861
227862
237862
247962
257962
268063
278063
288064
298064
308164
318164

How May really feels in Marion

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.

Marion 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
Jan42° / 28°3.492.39.70.3
Feb47° / 31°3.18.12.310.51.5
Mar57° / 39°4.211.40.911.74.0
Apr68° / 49°5.011.4012.96.0
May76° / 60°4.612.60146.3
Jun85° / 68°3.610.6014.65.2
Jul88° / 72°3.510.2014.34.5
Aug87° / 69°2.88.1013.55.1
Sep81° / 61°2.97.5012.36.9
Oct69° / 50°3.57.60116.9
Nov56° / 39°3.88.70.5103.9
Dec46° / 31°3.38.91.89.41.2

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 26% 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 58%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
14258
24258
34258
44258
54159
64159
74159
84159
94258
104258
114159
124159
134258
144258
154258
164159
174159
184159
194060
204159
214060
224258
234159
244159
254258
264258
274357
284357
294456
304555
314555

Chance of precipitation in May

Any precipitation

Marion gets around 4.6 in of rain over 12.6 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 45% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%151015202531
Rain chance (%)
145
245
344
444
544
644
743
843
943
1042
1142
1242
1341
1441
1541
1640
1740
1840
1940
2040
2139
2239
2339
2438
2538
2638
2738
2838
2938
3038
3137

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 44% of days. Sticky, muggy-or-worse air turns up on roughly 20% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
163191440
262191540
360191650
458191760
557191770
655191880
754191890
8531918100
9511919110
10501819130
11491819140
12481819150
13481719160
14471719170
15461719181
16451619191
17441619201
18431519221
19421519232
20401519242
21391519252
22371520263
23361520273
24341521283
25321521284
26311522294
27291522294
28281523304
29261623305
30251624315
31241624315

Wind in May

Winds average 7 mph in May.

Across May, daily wind ranges from about 6 mph on the calmest days to 8 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
18light breeze
28light breeze
38light breeze
48light breeze
58light breeze
68light breeze
77light breeze
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227calm
237calm
247calm
257calm
267calm
277calm
287calm
297calm
306calm
316calm

Sunrise & sunset in May

DaylightNight

Daylight runs from about 13 h 30 min at the start of May to 14 h 24 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 54 minutes over May. Sunrise moves from 5:07 AM to 4:41 AM, and sunset from 6:39 PM to 7:05 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
113.55:076:39
213.65:066:40
313.65:046:41
413.65:036:42
513.75:026:43
613.75:016:44
713.75:006:45
813.84:596:46
913.84:586:47
1013.84:576:47
1113.94:566:48
1213.94:556:49
1313.94:546:50
1414.04:536:51
1514.04:526:52
1614.04:516:53
1714.14:506:54
1814.14:496:55
1914.14:496:55
2014.14:486:56
2114.24:476:57
2214.24:466:58
2314.24:466:59
2414.24:457:00
2514.34:457:00
2614.34:447:01
2714.34:437:02
2814.34:437:03
2914.44:427:03
3014.44:427:04
3114.44:417:05

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.84 kWh/m².

For context, solar energy here swings from a low near 1.93 kWh/m² to a high of 6.45 kWh/m² in June across the year — May's 5.84 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.4Bright
25.5Bright
35.5Bright
45.5Bright
55.5Bright
65.6Bright
75.6Bright
85.7Bright
95.7Bright
105.7Bright
115.8Bright
125.8Bright
135.8Bright
145.8Bright
155.9Bright
165.9Bright
175.9Bright
186.0Bright
196.0Bright
206.0Bright
216.0Intense
226.0Intense
236.0Intense
246.0Intense
256.1Intense
266.1Intense
276.1Intense
286.1Intense
296.1Intense
306.1Intense
316.1Intense
Planning a trip in May

Is May a good time to visit Marion?

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

6.3
Sightseeing
3rd-best month of the year
5.6
Beach & pool
5th-best month of the year

May is a reasonable time to visit Marion for sightseeing.

What to pack for Marion in May

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

In May, Marion sees daytime highs around 76°F and nights near 60°F. Worth packing: light clothes, rain gear and sun protection. About 13 days see rain.

light clothesrain gearsun protection

UV index in Marion 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 Marion peaks around June 23 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 at about 2 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 10 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateJun 23UV 9Dec 22UV 2
UV index (midday)Level
Jan2Moderate
Feb4Moderate
Mar5High
Apr7High
May8Very high
Jun9Very high
Jul9Very high
Aug8Very high
Sep7High
Oct4Moderate
Nov3Moderate
Dec2Moderate

Air quality in Marion 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 Marion is worst in July — around 19 µg/m³ PM2.5 (moderate), about 2.4× the cleanest month (November, 8 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1318 µg/m³Nov 128 µg/m³
PM2.5 (µg/m³)Level
Jan8Good
Feb11Good
Mar12Moderate
Apr11Good
May14Moderate
Jun17Moderate
Jul19Moderate
Aug14Moderate
Sep12Good
Oct8Good
Nov8Good
Dec8Good
Location & terrain

Where is Marion?

Marion sits at 37.7°N, 88.9°W, 423 ft above sea level, in United States. The nearest listed city is Carbondale, 16 mi away.

Topography around Marion

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

Within 2 miles, the terrain around Marion has only modest variations in elevation — a maximum elevation change of 148 ft around an average of 446 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 331 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 1,030 ft.

The land around Marion is covered by trees (32%), grassland (26%) and artificial surfaces (24%) within 2 miles, trees (51%), grassland (21%) and cropland (20%) within 10 miles, and trees (46%) and cropland (40%) within 50 miles.

2 miles
148 ft
10 miles
331 ft
50 miles
1,030 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
May weather nearby: Carbondale 16 mi · Mount Vernon 40 mi · Cape Girardeau 43 mi · Paducah 48 mi · Sikeston 69 mi · Henderson 74 mi · Evansville 77 mi · Belleville 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 Marion (37.7306°, -88.9331°, elevation 423 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).