Decatur weather in July

In July, Decatur sees average daytime highs of 84°F and overnight lows near 67°F, with 3.6 in of rain across 10.3 wet days and about 14.5 hours of daylight. It is the 1st-warmest and 4th-wettest month of the year here.

Day-to-day highs hold fairly steady near 84°F through the month. The sky is clear or mostly clear about 39% of the time in July, and the air most often feels muggy.

Daylight stretches from about 14 h 48 min at the start of July to 14 h 12 min by month's end. Set against the rest of the year, July is Decatur's 3rd-clearest and 11th-windiest month. For the whole year in context, see Decatur's year-round climate.

Daytime high
84°
1st warmest
Overnight low
67°
12th coldest
Rainfall
3.6 in
10.3 wet days
Daylight
14 h 36 min
4:44 AM – 7:18 PM
Cloud cover
52%
3rd clearest
Wind
6 mph
11th windiest
Solar energy
6.41 kWh/m²
Travel score
5.5
out of 10

Decatur is city in Macon County, Illinois, United States.

Density
602/km²
people per km²
Founded
1823

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

Temperature in July

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 84°F through the month.

A typical July day in Decatur reaches about 84°F in the afternoon and slips back to 67°F overnight — a 17°F spread between the day's warmth and the night's chill. On most days the high lands between 77°F and 92°F. Set against its neighbours, July runs about 3°F warmer than June and on par with August.

50°60°70°80°90°151015202531
Avg high (°F)Avg low (°F)
18467
28467
38467
48467
58467
68467
78467
88567
98568
108568
118568
128568
138568
148568
158568
168568
178568
188568
198568
208568
218568
228568
238468
248467
258467
268467
278467
288467
298467
308467
318467

How July really feels in Decatur

Once humidity and wind are folded in, July 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

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

Decatur weather by month

How July compares with the rest of the year at a glance. July is the 1st-warmest and 4th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan36° / 21°2.78.549.50.0
Feb40° / 24°2.37.53.410.40.2
Mar52° / 34°3.39.71.511.72.7
Apr64° / 44°4.611.80.3135.3
May73° / 55°4.813.2014.26.2
Jun82° / 64°4.310.9014.86.0
Jul84° / 67°3.610.3014.55.5
Aug83° / 65°3.08.5013.66.1
Sep78° / 57°3.27.4012.37.3
Oct65° / 46°3.58.60.110.96.2
Nov51° / 35°3.58.70.89.82.7
Dec40° / 26°2.58.72.99.20.2

Cloud cover in July

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 39% of the time in July.

Beyond those clear spells, partly cloudy skies cover about 18% of July, with mostly cloudy or overcast conditions the remaining 43%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
15743
25743
35842
45842
55842
65842
75941
85941
95941
105941
115941
125941
135842
145842
155743
165743
175743
185743
195644
205644
215644
225644
235644
245644
255644
265743
275743
285743
295842
305842
315842

Chance of precipitation in July

Any precipitation

Decatur gets around 3.6 in of rain over 10.3 wet days in July. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 33% and peaks near 34% on the wettest days.

0%10%20%30%40%151015202531
Rain chance (%)
134
234
334
434
533
633
733
833
933
1033
1133
1233
1334
1434
1534
1634
1734
1834
1934
2034
2134
2234
2333
2433
2533
2632
2732
2831
2931
3030
3130

Humidity in July

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, July lands in the muggy band about 29% of days. Sticky, muggy-or-worse air turns up on roughly 59% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
17172033220
27171933230
37171933230
47171932241
57172031251
66162031251
76162031261
86152131261
96152131261
105142131272
115132131272
125132131282
135132131283
144132131293
154132130293
164132130294
174132129304
184122129304
194122129304
204122128314
214122128314
224132127314
235132227313
245132226313
255142226313
265142325303
275142425292
285152425292
295152525282
305152526271
315162526271

Wind in July

Winds average 6 mph in July.

Across July, 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
17calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm
316calm

Sunrise & sunset in July

DaylightNight

Daylight runs from about 14 h 48 min at the start of July to 14 h 12 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 36 minutes over July. Sunrise moves from 4:35 AM to 4:57 AM, and sunset from 7:23 PM to 7:07 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
114.84:357:23
214.84:367:23
314.84:367:23
414.84:377:23
514.84:377:22
614.74:387:22
714.74:387:22
814.74:397:22
914.74:407:21
1014.74:407:21
1114.74:417:21
1214.64:427:20
1314.64:427:20
1414.64:437:19
1514.64:447:19
1614.64:447:18
1714.54:457:18
1814.54:467:17
1914.54:477:17
2014.54:487:16
2114.44:487:15
2214.44:497:15
2314.44:507:14
2414.44:517:13
2514.34:527:12
2614.34:537:11
2714.34:547:10
2814.34:547:10
2914.24:557:09
3014.24:567:08
3114.24:577:07

Solar energy in July

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in July, about 6.41 kWh/m².

For context, solar energy here swings from a low near 1.8 kWh/m² to a high of 6.44 kWh/m² in June across the year — July's 6.41 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
16.5Intense
26.5Intense
36.5Intense
46.5Intense
56.5Intense
66.5Intense
76.5Intense
86.5Intense
96.5Intense
106.5Intense
116.5Intense
126.5Intense
136.5Intense
146.5Intense
156.5Intense
166.5Intense
176.4Intense
186.4Intense
196.4Intense
206.4Intense
216.4Intense
226.3Intense
236.3Intense
246.3Intense
256.3Intense
266.3Intense
276.3Intense
286.3Intense
296.2Intense
306.2Intense
316.2Intense
Planning a trip in July

Hazard calendar for Decatur

In seasonPeak

In July, Decatur sits inside its atlantic hurricane season. The full year is below, with each hazard's peak months called out.

Decatur sits in the Atlantic hurricane belt; the season peaks August–October.

Atlantic hurricane
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is July a good time to visit Decatur?

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

5.5
Sightseeing
6th-best month of the year
7.1
Beach & pool
2nd-best month of the year

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

What to pack for Decatur in July

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

In July, Decatur sees daytime highs around 84°F and nights near 67°F. Pack light clothes and sun protection. Worth having: rain gear. About 10 days see rain.

light clothessun protectionrain gear

UV index in Decatur in July

LowModerateHighVery highExtreme

Clear-sky midday UV in July peaks around 9 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Decatur peaks around June 22 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 1 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 22UV 9Jan 1UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May8Very high
Jun9Very high
Jul9Very high
Aug8Very high
Sep6High
Oct4Moderate
Nov3Moderate
Dec2Low

Air quality in Decatur in July

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Decatur is worst in July — around 17 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (October, 8 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodModerateGoodJul 1716 µg/m³Oct 228 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb13Moderate
Mar12Moderate
Apr11Good
May14Moderate
Jun14Moderate
Jul17Moderate
Aug15Moderate
Sep12Good
Oct8Good
Nov8Good
Dec9Good
Location & terrain

Where is Decatur?

Decatur sits at 39.8°N, 89.0°W, 673 ft above sea level, in United States. The nearest listed city is Springfield, 37 mi away.

Topography around Decatur

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

Within 2 miles, the terrain around Decatur has only modest variations in elevation — a maximum elevation change of 164 ft around an average of 666 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 197 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 489 ft.

The land around Decatur is covered by trees (43%) and artificial surfaces (34%) within 2 miles, cropland (68%) within 10 miles, and cropland (83%) within 50 miles.

2 miles
164 ft
10 miles
197 ft
50 miles
489 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
July weather nearby: Springfield 37 mi · Mattoon 40 mi · Champaign 42 mi · Urbana 43 mi · Bloomington 45 mi · Normal 47 mi · Charleston 48 mi · Morton 60 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 Decatur (39.8403°, -88.9548°, elevation 673 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. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). 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).