Marion weather in August

In August, Marion sees average daytime highs of 87°F and overnight lows near 69°F, with 2.8 in of rain across 8.1 wet days and about 13.5 hours of daylight. It is the 2nd-warmest and 12th-wettest month of the year here.

Day-to-day highs hold fairly steady near 87°F through the month. The sky is clear or mostly clear about 42% of the time in August, and the air most often feels muggy.

Daylight stretches from about 14 hours at the start of August to 12 h 54 min by month's end. Set against the rest of the year, August is Marion's 3rd-clearest and 12th-windiest month. For the whole year in context, see Marion's year-round climate.

Daytime high
87°
2nd warmest
Overnight low
69°
11th coldest
Rainfall
2.8 in
8.1 wet days
Daylight
13 h 30 min
5:16 AM – 6:44 PM
Cloud cover
50%
3rd clearest
Wind
5 mph
12th windiest
Solar energy
5.8 kWh/m²
Travel score
5.1
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 August

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 87°F through the month.

A typical August day in Marion reaches about 87°F in the afternoon and slips back to 69°F overnight — a 17°F spread between the day's warmth and the night's chill. On most days the high lands between 80°F and 94°F. Set against its neighbours, August runs on par with July and about 6°F warmer than September.

60°70°80°90°151015202531
Avg high (°F)Avg low (°F)
18871
28771
38771
48770
58770
68770
78770
88770
98770
108770
118770
128770
138769
148769
158769
168769
178769
188769
198769
208769
218769
228769
238769
248769
258769
268669
278668
288668
298668
308668
318667

How August really feels in Marion

Once humidity and wind are folded in, August averages 9 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
9
heat index over the day's high
Days feeling ≤ 32°F
0
wind chill below the day's low

The story in August is heat — humidity pushes the afternoon "feels like" well above the raw temperature.

Marion weather by month

How August compares with the rest of the year at a glance. August is the 2nd-warmest and 12th-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 August

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 42% of the time in August.

Beyond those clear spells, partly cloudy skies cover about 19% of August, with mostly cloudy or overcast conditions the remaining 39%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
16040
26040
36040
46139
56139
66139
76040
86040
96040
106040
116040
125941
135941
145941
156040
166139
176139
186139
196139
206139
216139
226139
236040
246040
256139
266139
276139
286238
296238
306238
316337

Chance of precipitation in August

Any precipitation

Marion gets around 2.8 in of rain over 8.1 wet days in August, the driest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 26% and peaks near 30% on the wettest days. The odds ease toward the end of the month.

0%10%20%30%40%151015202531
Rain chance (%)
130
230
330
430
530
629
729
829
929
1028
1128
1228
1327
1427
1526
1625
1725
1824
1924
2024
2124
2224
2324
2424
2524
2624
2724
2824
2924
3024
3124

Humidity in August

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, August lands in the muggy band about 30% of days. Sticky, muggy-or-worse air turns up on roughly 62% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
12112029362
22112029362
32112030352
43112030342
53112130342
63112130332
73112030332
84112030322
94112030322
104122030322
114122030322
125131930312
135131930312
145141930302
155141930302
165142030302
175142030292
185142030292
195142030291
205142031291
215142031291
225132131291
235132131291
245132131291
256132131291
266132131280
276132132270
287132132260
298142232250
308142232240
319152232230

Wind in August

Winds average 5 mph in August, the calmest month.

Across August, daily wind ranges from about 5 mph on the calmest days to 6 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
15calm
25calm
35calm
45calm
55calm
65calm
75calm
85calm
95calm
105calm
115calm
125calm
135calm
145calm
155calm
165calm
175calm
185calm
195calm
205calm
215calm
225calm
235calm
245calm
255calm
265calm
276calm
286calm
296calm
306calm
316calm

Sunrise & sunset in August

DaylightNight

Daylight runs from about 14 hours at the start of August to 12 h 54 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 66 minutes over August. Sunrise moves from 5:03 AM to 5:29 AM, and sunset from 7:01 PM to 6:23 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
114.05:037:01
213.95:047:00
313.95:046:59
413.95:056:58
513.85:066:57
613.85:076:56
713.85:086:55
813.75:096:54
913.75:106:52
1013.75:116:51
1113.65:116:50
1213.65:126:49
1313.65:136:48
1413.55:146:46
1513.55:156:45
1613.55:166:44
1713.45:176:43
1813.45:186:41
1913.45:186:40
2013.35:196:39
2113.35:206:37
2213.25:216:36
2313.25:226:34
2413.25:236:33
2513.15:246:31
2613.15:256:30
2713.15:256:29
2813.05:266:27
2913.05:276:26
3012.95:286:24
3112.95:296:23

Solar energy in August

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in August, about 5.8 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 — August's 5.8 kWh/m² falls in the middle.

0246151015202531
Solar energy (kWh/m²)Level
16.1Intense
26.1Intense
36.1Intense
46.1Intense
56.0Intense
66.0Intense
76.0Intense
86.0Bright
95.9Bright
105.9Bright
115.9Bright
125.9Bright
135.8Bright
145.8Bright
155.8Bright
165.8Bright
175.8Bright
185.7Bright
195.7Bright
205.7Bright
215.7Bright
225.6Bright
235.6Bright
245.6Bright
255.5Bright
265.5Bright
275.5Bright
285.4Bright
295.4Bright
305.4Bright
315.3Bright
Planning a trip in August

Is August a good time to visit Marion?

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

5.1
Sightseeing
6th-best month of the year
7.2
Beach & pool
1st-best month of the year

August is a reasonable time to visit Marion for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Marion in August

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

In August, Marion sees daytime highs around 87°F and nights near 69°F. Pack light clothes. Worth having: rain gear and sun protection. About 8 days see rain.

light clothesrain gearsun protection

UV index in Marion in August

LowModerateHighVery highExtreme

Clear-sky midday UV in August peaks around 8 (very high — sun protection essential). 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 August

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where August 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
August 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).