Macomb weather in September

In September, Macomb sees average daytime highs of 77°F and overnight lows near 57°F, with 3.4 in of rain across 7.6 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 4th-wettest month of the year here.

Highs ease over the month, from about 81°F in the first days to 72°F by the end. The sky is clear or mostly clear about 48% of the time in September, and the air most often feels dry.

Daylight stretches from about 12 h 54 min at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Macomb's 1st-clearest and 9th-windiest month. For the whole year in context, see Macomb's year-round climate.

Daytime high
77°
4th warmest
Overnight low
57°
9th coldest
Rainfall
3.4 in
7.6 wet days
Daylight
12 h 18 min
5:49 AM – 6:05 PM
Cloud cover
45%
1st clearest
Wind
7 mph
9th windiest
Solar energy
4.71 kWh/m²
Travel score
7.3
out of 10

Macomb is city in and the county seat of McDonough County, Illinois, United States.

Density
644/km²
people per km²
Founded
1830

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

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 81°F in the first days to 72°F by the end.

A typical September day in Macomb reaches about 77°F in the afternoon and slips back to 57°F overnight — a 20°F spread between the day's warmth and the night's chill. On most days the high lands between 66°F and 87°F. Set against its neighbours, September runs about 6°F cooler than August and about 12°F warmer than October.

40°60°80°151015202530
Avg high (°F)Avg low (°F)
18262
28162
38162
48161
58061
68060
78060
87960
97959
107959
117858
127858
137858
147757
157757
167756
177656
187656
197655
207555
217554
227454
237454
247453
257353
267352
277352
287252
297251
307251

How September really feels in Macomb

Once humidity and wind are folded in, September 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

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

Macomb weather by month

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

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan33° / 19°2.07.64.99.40.0
Feb38° / 22°2.173.810.40.1
Mar50° / 32°2.99.6211.72.3
Apr62° / 43°4.611.90.4135.0
May73° / 54°4.713014.26.2
Jun82° / 64°4.811.7014.85.9
Jul85° / 67°3.39.7014.65.5
Aug83° / 65°3.29.1013.66.1
Sep77° / 57°3.47.6012.37.3
Oct64° / 45°2.88.50.210.95.9
Nov50° / 34°2.7819.82.3
Dec38° / 24°2.173.29.20.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 48% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 12% of September, with mostly cloudy or overcast conditions the remaining 40%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16436
26436
36436
46436
56436
66436
76436
86337
96337
106238
116139
126139
136040
145941
155842
165842
175743
185743
195743
205743
215743
225941
235941
245941
255941
265941
276040
286040
296040
306040

Chance of precipitation in September

Any precipitation

Macomb gets around 3.4 in of rain over 7.6 wet days in September. 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 28% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
128
228
328
428
528
628
728
828
928
1028
1128
1228
1328
1428
1528
1627
1727
1827
1926
2025
2125
2224
2324
2424
2523
2623
2723
2823
2923
3023

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the dry band about 46% of days. Sticky, muggy-or-worse air turns up on roughly 18% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
11823212810
2202321279
3222421268
4242421248
5262420237
6282420216
7302420206
8322420195
9342420185
10362319174
11382319174
12402218163
13422218153
14442217153
15462116142
16482116142
17502115132
18512014132
19532014121
20561913111
21561913111
22581912101
2360181291
2463181180
2564171180
2665171170
2767171060
2868161060
2969161050
307115950

Wind in September

Winds average 7 mph in September.

Across September, daily wind ranges from about 7 mph on the calmest days to 8 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
17calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217light breeze
228light breeze
238light breeze
248light breeze
258light breeze
268light breeze
278light breeze
288light breeze
298light breeze
308light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 54 min at the start of September to 11 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 78 minutes over September. Sunrise moves from 5:34 AM to 6:03 AM, and sunset from 6:31 PM to 5:41 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.95:346:31
212.95:356:29
312.95:366:27
412.85:376:26
512.85:386:24
612.75:396:22
712.75:406:21
812.65:416:19
912.65:426:17
1012.55:436:15
1112.55:446:14
1212.45:456:12
1312.45:466:10
1412.45:476:08
1512.35:486:07
1612.35:496:05
1712.25:506:03
1812.25:516:01
1912.15:526:00
2012.15:535:58
2112.05:545:56
2212.05:555:54
2311.95:565:53
2411.95:575:51
2511.95:585:49
2611.85:595:48
2711.86:005:46
2811.76:015:44
2911.76:025:42
3011.66:035:41

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.71 kWh/m².

For context, solar energy here swings from a low near 1.8 kWh/m² to a high of 6.43 kWh/m² in June across the year — September's 4.71 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.2Bright
25.2Bright
35.2Bright
45.1Bright
55.1Bright
65.1Bright
75.0Bright
85.0Bright
95.0Bright
104.9Bright
114.9Bright
124.8Bright
134.8Bright
144.7Bright
154.7Bright
164.7Bright
174.6Bright
184.6Bright
194.5Bright
204.5Bright
214.5Bright
224.4Bright
234.4Bright
244.3Bright
254.3Bright
264.3Bright
274.2Bright
284.2Bright
294.1Bright
304.1Bright
Planning a trip in September

Is September a good time to visit Macomb?

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

7.3
Sightseeing
1st-best month of the year
6.4
Beach & pool
4th-best month of the year

September is one of the better times to visit Macomb for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Macomb in September

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

In September, Macomb sees daytime highs around 77°F and nights near 57°F. Worth packing: light clothes and sun protection. About 8 days see rain.

light clothessun protection

UV index in Macomb in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Macomb peaks around June 19 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 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 highHighModerateJun 19UV 9Dec 21UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5Moderate
Apr6High
May8Very high
Jun9Very high
Jul9Very high
Aug8Very high
Sep7High
Oct3Moderate
Nov3Moderate
Dec2Low

Air quality in Macomb in September

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Macomb is worst in July — around 16 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (October, 7 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodModerateGoodJul 1815 µg/m³Oct 227 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb13Moderate
Mar12Good
Apr10Good
May13Moderate
Jun13Moderate
Jul16Moderate
Aug14Moderate
Sep11Good
Oct7Good
Nov8Good
Dec9Good
Location & terrain

Where is Macomb?

Macomb sits at 40.5°N, 90.7°W, 705 ft above sea level, in United States. The nearest listed city is Burlington, 34 mi away.

Topography around Macomb

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

Within 2 miles, the terrain around Macomb has only modest variations in elevation — a maximum elevation change of 141 ft around an average of 682 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 256 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 472 ft.

The land around Macomb is covered by trees (32%), cropland (27%) and grassland (23%) within 2 miles, cropland (73%) within 10 miles, and cropland (63%) and trees (27%) within 50 miles.

2 miles
141 ft
10 miles
256 ft
50 miles
472 ft
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Burlington 34 mi · Galesburg 37 mi · Quincy 53 mi · Pekin 55 mi · Jacksonville 55 mi · East Peoria 59 mi · Peoria 59 mi · North Peoria 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 Macomb (40.4592°, -90.6718°, elevation 705 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).