DeKalb weather in July

In July, DeKalb sees average daytime highs of 82°F and overnight lows near 64°F, with 3.5 in of rain across 10.7 wet days and about 14.7 hours of daylight. It is the 1st-warmest and 4th-wettest month of the year here.

Day-to-day highs hold fairly steady near 82°F through the month. The sky is clear or mostly clear about 34% of the time in July, and the air most often feels muggy.

Daylight stretches from about 15 hours at the start of July to 14 h 18 min by month's end. Set against the rest of the year, July is DeKalb's 3rd-clearest and 11th-windiest month. For the whole year in context, see DeKalb's year-round climate.

Daytime high
82°
1st warmest
Overnight low
64°
12th coldest
Rainfall
3.5 in
10.7 wet days
Daylight
14 h 48 min
4:38 AM – 7:24 PM
Cloud cover
55%
3rd clearest
Wind
7 mph
11th windiest
Solar energy
6.21 kWh/m²
Travel score
6.4
out of 10

DeKalb is city in De Kalb County, Illinois, United States.

Density
1,080/km²
people per km²
Founded
1837

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 82°F through the month.

A typical July day in DeKalb reaches about 82°F in the afternoon and slips back to 64°F overnight — a 17°F spread between the day's warmth and the night's chill. On most days the high lands between 74°F and 89°F. Set against its neighbours, July runs about 3°F warmer than June and about 2°F warmer than August.

50°60°70°80°90°151015202531
Avg high (°F)Avg low (°F)
18164
28164
38164
48164
58264
68264
78264
88264
98264
108264
118264
128265
138265
148265
158265
168265
178265
188265
198265
208265
218265
228265
238265
248265
258264
268264
278264
288164
298164
308164
318164

How July really feels in DeKalb

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.

DeKalb 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
Jan29° / 16°2.07.65.79.30.0
Feb34° / 19°1.86.94.910.30.0
Mar46° / 29°2.69.32.911.71.3
Apr59° / 40°4.4120.913.14.1
May69° / 50°4.812.8014.35.9
Jun78° / 60°4.212.20156.3
Jul82° / 64°3.510.7014.76.4
Aug80° / 62°3.510.4013.76.6
Sep74° / 54°3.28.7012.37.0
Oct61° / 43°3.19.10.110.95.2
Nov47° / 32°2.47.71.69.61.5
Dec35° / 22°2.27.84.590.0

Cloud cover in July

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 34% of the time in July.

Beyond those clear spells, partly cloudy skies cover about 21% of July, with mostly cloudy or overcast conditions the remaining 45%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
15644
25644
35644
45644
55644
65545
75545
85644
95644
105545
115545
125545
135446
145347
155347
165347
175248
185248
195248
205248
215248
225347
235446
245446
255446
265545
275545
285644
295743
305743
315743

Chance of precipitation in July

Any precipitation

DeKalb gets around 3.5 in of rain over 10.7 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 35% and peaks near 36% on the wettest days.

0%10%20%30%40%50%151015202531
Rain chance (%)
136
236
336
435
535
635
734
834
934
1034
1134
1234
1335
1435
1535
1635
1735
1835
1935
2035
2135
2236
2336
2436
2535
2635
2735
2835
2934
3034
3134

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 27% of days. Sticky, muggy-or-worse air turns up on roughly 42% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
119212227100
219212226110
319212326110
419202326121
518202326121
618202426121
717202426121
817192426131
916192527131
1015192527131
1114182528141
1214182528141
1313182528151
1413172528151
1512172629151
1612172528162
1712172528162
1812172528162
1911172528162
2011172528172
2111182528172
2211182528172
2310192527172
2410202527162
2510212527162
2610212526152
2711222526152
2811232526142
2911232526131
3011242526131
3111252525121

Wind in July

Winds average 7 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
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227calm
237calm
247calm
256calm
266calm
276calm
286calm
296calm
306calm
316calm

Sunrise & sunset in July

DaylightNight

Daylight runs from about 15 hours at the start of July to 14 h 18 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 42 minutes over July. Sunrise moves from 4:28 AM to 4:51 AM, and sunset from 7:29 PM to 7:11 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
115.04:287:29
215.04:287:29
315.04:297:29
415.04:297:28
515.04:307:28
615.04:307:28
714.94:317:28
814.94:327:27
914.94:327:27
1014.94:337:27
1114.94:347:26
1214.94:347:26
1314.84:357:25
1414.84:367:25
1514.84:377:24
1614.84:387:24
1714.74:387:23
1814.74:397:22
1914.74:407:22
2014.74:417:21
2114.64:427:20
2214.64:437:19
2314.64:447:19
2414.64:447:18
2514.54:457:17
2614.54:467:16
2714.54:477:15
2814.44:487:14
2914.44:497:13
3014.44:507:12
3114.34:517:11

Solar energy in July

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in July, about 6.21 kWh/m².

For context, solar energy here swings from a low near 1.69 kWh/m² to a high of 6.29 kWh/m² in June across the year — July's 6.21 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
16.4Intense
26.4Intense
36.4Intense
46.4Intense
56.4Intense
66.4Intense
76.3Intense
86.3Intense
96.3Intense
106.3Intense
116.3Intense
126.3Intense
136.3Intense
146.2Intense
156.2Intense
166.2Intense
176.2Intense
186.2Intense
196.1Intense
206.1Intense
216.1Intense
226.1Intense
236.1Intense
246.1Intense
256.0Intense
266.0Intense
276.0Intense
286.0Intense
296.0Bright
306.0Bright
315.9Bright
Planning a trip in July

Is July a good time to visit DeKalb?

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

6.4
Sightseeing
3rd-best month of the year
6.7
Beach & pool
1st-best month of the year

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

What to pack for DeKalb in July

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

In July, DeKalb sees daytime highs around 82°F and nights near 64°F. Pack light clothes and sun protection. Worth having: rain gear. About 11 days see rain.

light clothessun protectionrain gear

UV index in DeKalb in July

LowModerateHighVery highExtreme

Clear-sky midday UV in July 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 DeKalb peaks around June 19 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 19 at about 2 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateLowJun 19UV 9Dec 19UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar4Moderate
Apr6High
May8Very high
Jun9Very high
Jul8Very high
Aug8Very high
Sep6High
Oct3Moderate
Nov2Moderate
Dec2Low

Air quality in DeKalb 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 DeKalb is worst in July — around 17 µg/m³ PM2.5 (moderate), about 1.9× the cleanest month (October, 9 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodJul 1817 µg/m³Oct 229 µg/m³
PM2.5 (µg/m³)Level
Jan12Moderate
Feb15Moderate
Mar16Moderate
Apr14Moderate
May15Moderate
Jun16Moderate
Jul17Moderate
Aug16Moderate
Sep13Moderate
Oct9Good
Nov10Good
Dec11Good
Location & terrain

Where is DeKalb?

DeKalb sits at 41.9°N, 88.8°W, 879 ft above sea level, in United States. The nearest listed city is Sycamore, 5.0 mi away.

Topography around DeKalb

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

Within 2 miles, the terrain around DeKalb has only modest variations in elevation — a maximum elevation change of 102 ft around an average of 883 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 308 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 850 ft.

The land around DeKalb is covered by artificial surfaces (35%), trees (23%) and grassland (23%) within 2 miles, cropland (84%) within 10 miles, and cropland (59%) within 50 miles.

2 miles
102 ft
10 miles
308 ft
50 miles
850 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
July weather nearby: Sycamore 5.0 mi · Wasco 18 mi · St. Charles 23 mi · Geneva 23 mi · Batavia 23 mi · Huntley 24 mi · North Aurora 24 mi · Belvidere 24 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 DeKalb (41.9295°, -88.7504°, elevation 879 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).