Mattoon weather in August

In August, Mattoon sees average daytime highs of 83°F and overnight lows near 65°F, with 3.0 in of rain across 8.5 wet days and about 13.5 hours of daylight. It is the 2nd-warmest and 8th-wettest month of the year here.

Day-to-day highs hold fairly steady near 83°F through the month. The sky is clear or mostly clear about 43% of the time in August, and the air most often feels muggy.

Daylight stretches from about 14 h 06 min at the start of August to 13 hours by month's end. Set against the rest of the year, August is Mattoon's 2nd-clearest and 12th-windiest month. For the whole year in context, see Mattoon's year-round climate.

Daytime high
83°
2nd warmest
Overnight low
65°
11th coldest
Rainfall
3.0 in
8.5 wet days
Daylight
13 h 36 min
5:11 AM – 6:44 PM
Cloud cover
51%
2nd clearest
Wind
6 mph
12th windiest
Solar energy
5.74 kWh/m²
Travel score
6.0
out of 10

Mattoon is city in Illinois, United States.

Density
676/km²
people per km²
Founded
1853

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 83°F through the month.

A typical August day in Mattoon reaches about 83°F in the afternoon and slips back to 65°F overnight — a 18°F spread between the day's warmth and the night's chill. On most days the high lands between 76°F and 91°F. Set against its neighbours, August runs on par with July and about 5°F warmer than September.

50°60°70°80°90°151015202531
Avg high (°F)Avg low (°F)
18467
28467
38467
48467
58466
68366
78366
88366
98366
108366
118366
128366
138366
148366
158365
168365
178365
188365
198365
208365
218365
228365
238365
248365
258365
268365
278365
288365
298364
308364
318364

How August really feels in Mattoon

Once humidity and wind are folded in, August 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

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

Mattoon weather by month

How August compares with the rest of the year at a glance. August is the 2nd-warmest and 8th-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°3.08.5013.56.0
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 August

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 43% of the time in August.

Beyond those clear spells, partly cloudy skies cover about 17% of August, with mostly cloudy or overcast conditions the remaining 40%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
15941
26040
36040
46040
56040
66040
76040
85941
95941
105941
115941
125941
135941
145941
155941
165941
175941
185941
196040
206040
216040
225941
236040
246139
256040
266139
276139
286139
296337
306337
316337

Chance of precipitation in August

Any precipitation

Mattoon gets around 3.0 in of rain over 8.5 wet days in August. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 27% and peaks near 31% on the wettest days.

0%10%20%30%40%151015202531
Rain chance (%)
131
230
330
429
529
628
728
828
928
1028
1127
1227
1327
1427
1527
1626
1726
1826
1926
2026
2127
2227
2327
2427
2527
2626
2726
2826
2926
3026
3126

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 27% of days. Sticky, muggy-or-worse air turns up on roughly 48% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
16172426271
25172426261
35172427251
45172428251
55182428240
66182428230
76182429230
86192429230
97192329220
107192328220
117192329210
128192328210
138202328211
148202427201
158212427201
169212427191
179212427191
189212427191
199212427191
2010212426191
2110202427181
2210202527181
2310202527180
2410202527180
2511202527170
2612202527170
2712202527160
2813202427160
2915202427150
3016192426140
3117192426130

Wind in August

Winds average 6 mph in August, the calmest month.

Across August, daily wind ranges from about 6 mph on the calmest days to 7 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (mph)Feels
16calm
26calm
36calm
46calm
56calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
287calm
297calm
307calm
317calm

Sunrise & sunset in August

DaylightNight

Daylight runs from about 14 h 06 min at the start of August to 13 hours by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 66 minutes over August. Sunrise moves from 4:57 AM to 5:25 AM, and sunset from 7:03 PM to 6:22 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
114.14:577:03
214.14:577:01
314.04:587:00
414.04:596:59
514.05:006:58
613.95:016:57
713.95:026:56
813.95:036:55
913.85:046:54
1013.85:056:52
1113.85:066:51
1213.75:076:50
1313.75:086:49
1413.65:096:47
1513.65:106:46
1613.65:116:44
1713.55:126:43
1813.55:136:42
1913.45:146:40
2013.45:156:39
2113.45:156:37
2213.35:166:36
2313.35:176:34
2413.25:186:33
2513.25:196:31
2613.25:206:30
2713.15:216:28
2813.15:226:27
2913.05:236:25
3013.05:246:24
3113.05:256:22

Solar energy in August

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in August, about 5.74 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 — August's 5.74 kWh/m² falls in the middle.

0246151015202531
Solar energy (kWh/m²)Level
16.2Intense
26.1Intense
36.1Intense
46.1Intense
56.0Intense
66.0Intense
76.0Bright
86.0Bright
95.9Bright
105.9Bright
115.9Bright
125.8Bright
135.8Bright
145.8Bright
155.7Bright
165.7Bright
175.7Bright
185.7Bright
195.6Bright
205.6Bright
215.6Bright
225.6Bright
235.5Bright
245.5Bright
255.5Bright
265.5Bright
275.4Bright
285.4Bright
295.4Bright
305.3Bright
315.3Bright
Planning a trip in August

Is August a good time to visit Mattoon?

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

6.0
Sightseeing
4th-best month of the year
7.3
Beach & pool
1st-best month of the year

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

What to pack for Mattoon in August

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

In August, Mattoon sees daytime highs around 83°F and nights near 65°F. Pack light clothes. Worth having: rain gear and sun protection. About 9 days see rain.

light clothesrain gearsun protection

UV index in Mattoon 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 Mattoon peaks around June 23 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 highHighModerateJun 23UV 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 Mattoon 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 Mattoon 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 Mattoon?

Mattoon sits at 39.5°N, 88.4°W, 735 ft above sea level, in United States. The nearest listed city is Charleston, 11 mi away.

Topography around Mattoon

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

Within 2 miles, the terrain around Mattoon has only modest variations in elevation — a maximum elevation change of 75 ft around an average of 712 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 236 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 446 ft.

The land around Mattoon is covered by cropland (49%) within 2 miles, cropland (80%) within 10 miles, and cropland (76%) within 50 miles.

2 miles
75 ft
10 miles
236 ft
50 miles
446 ft
treesgrasslandcroplandartificial surfaceswater
August weather nearby: Charleston 11 mi · Decatur 40 mi · Urbana 44 mi · Champaign 44 mi · Terre Haute 51 mi · Danville 59 mi · Springfield 71 mi · Vincennes 71 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 Mattoon (39.4831°, -88.3728°, elevation 735 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).