Zion weather in September

In September, Zion sees average daytime highs of 70°F and overnight lows near 64°F, with 3.1 in of rain across 9.7 wet days and about 12.3 hours of daylight. It is the 3rd-warmest and 7th-wettest month of the year here.

Highs ease over the month, from about 74°F in the first days to 65°F by the end. The sky is clear or mostly clear about 44% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 hours at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Zion's 1st-clearest and 8th-windiest month. For the whole year in context, see Zion's year-round climate.

Daytime high
70°
3rd warmest
Overnight low
64°
10th coldest
Rainfall
3.1 in
9.7 wet days
Daylight
12 h 18 min
5:37 AM – 5:54 PM
Cloud cover
49%
1st clearest
Wind
13 mph
8th windiest
Solar energy
4.39 kWh/m²
Travel score
6.7
out of 10

Zion is city in Lake County, Illinois, United States.

Density
949/km²
people per km²
Founded
1901

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 74°F in the first days to 65°F by the end.

A typical September day in Zion reaches about 70°F in the afternoon and slips back to 64°F overnight — a 6°F spread between the day's warmth and the night's chill. On most days the high lands between 62°F and 77°F. Set against its neighbours, September runs about 6°F cooler than August and about 12°F warmer than October.

50°60°70°80°151015202530
Avg high (°F)Avg low (°F)
17568
27468
37468
47468
57467
67367
77367
87366
97266
107266
117265
127165
137165
147164
157064
167064
177063
186963
196962
206862
216862
226861
236761
246760
256660
266659
276559
286559
296558
306458

How September really feels in Zion

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.

Zion weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 7th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan30° / 22°2.79.679.20.0
Feb30° / 21°2.27.55.410.30.0
Mar36° / 28°2.79.63.611.60.0
Apr44° / 38°4.511.81.513.10.8
May55° / 49°3.811.2014.43.5
Jun69° / 62°3.210.10156.3
Jul77° / 70°2.89.9014.87.0
Aug76° / 70°3.710.6013.77.0
Sep70° / 64°3.19.7012.36.7
Oct58° / 51°3.810.80.110.84.3
Nov46° / 39°3.29.71.39.61.1
Dec36° / 29°2.89.84.98.90.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 44% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 13% of September, with mostly cloudy or overcast conditions the remaining 43%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16139
26139
36238
46238
56337
66238
76238
86139
96139
106139
116040
126040
135941
145941
155842
165842
175644
185644
195644
205644
215446
225446
235446
245446
255347
265248
275248
285248
295248
305347

Chance of precipitation in September

Any precipitation

Zion gets around 3.1 in of rain over 9.7 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 33% and peaks near 35% on the wettest days.

0%10%20%30%40%50%151015202530
Rain chance (%)
130
230
330
430
530
630
730
831
931
1031
1132
1232
1333
1433
1534
1634
1734
1834
1934
2034
2135
2235
2335
2435
2535
2635
2735
2835
2935
3034

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 37% of days. Sticky, muggy-or-worse air turns up on roughly 19% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
11521242911
21621242810
31722242710
4192224269
5202324258
6222324257
7232324246
8252324235
9262324225
10282324214
11292324204
12302324193
13322324183
14332324173
15352324162
16372324142
17382323132
18402323121
19422422111
20442421101
2146242091
2248241991
2350241880
2453231770
2554231670
2656231560
2758221460
2861211350
2962211250
3064201240

Wind in September

Winds average 13 mph in September.

Across September, daily wind ranges from about 12 mph on the calmest days to 14 mph at its breeziest. It stays fairly steady from day to day.

05101520151015202530
Wind speed (mph)Feels
112light breeze
212light breeze
312light breeze
412light breeze
512light breeze
612light breeze
712light breeze
812light breeze
912light breeze
1012light breeze
1112light breeze
1212breezy
1313breezy
1413breezy
1513breezy
1613breezy
1713breezy
1813breezy
1913breezy
2013breezy
2113breezy
2213breezy
2313breezy
2413breezy
2513breezy
2614breezy
2714breezy
2814breezy
2914breezy
3014breezy

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 hours 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 84 minutes over September. Sunrise moves from 5:21 AM to 5:53 AM, and sunset from 6:21 PM to 5:28 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.05:216:21
213.05:226:20
312.95:236:18
412.95:246:16
512.85:256:14
612.85:266:12
712.75:276:11
812.75:286:09
912.65:306:07
1012.65:316:05
1112.55:326:03
1212.55:336:01
1312.45:346:00
1412.45:355:58
1512.35:365:56
1612.35:375:54
1712.25:385:52
1812.25:395:50
1912.15:405:49
2012.15:425:47
2112.05:435:45
2212.05:445:43
2311.95:455:41
2411.95:465:39
2511.85:475:38
2611.85:485:36
2711.75:495:34
2811.75:515:32
2911.65:525:30
3011.65:535:28

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.39 kWh/m².

For context, solar energy here swings from a low near 1.44 kWh/m² to a high of 6.49 kWh/m² in June across the year — September's 4.39 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.0Bright
25.0Bright
34.9Bright
44.9Bright
54.9Bright
64.8Bright
74.8Bright
84.7Bright
94.7Bright
104.6Bright
114.6Bright
124.5Bright
134.5Bright
144.4Bright
154.4Bright
164.3Bright
174.3Bright
184.3Bright
194.2Bright
204.2Bright
214.1Bright
224.1Bright
234.0Bright
244.0Bright
254.0Moderate
263.9Moderate
273.9Moderate
283.8Moderate
293.8Moderate
303.7Moderate
Planning a trip in September

Is September a good time to visit Zion?

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

6.7
Sightseeing
3rd-best month of the year
4.1
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Zion for sightseeing.

What to pack for Zion in September

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

In September, Zion sees daytime highs around 70°F and nights near 64°F. Worth packing: rain gear and a windbreaker. About 10 days see rain.

rain geara windbreaker

Sea temperature near Zion in September

The nearest coast averages about 67°F in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea offshore is warmest in August at about 71°F and coldest in March near 36°F.

It's comfortable for a long swim from Jul 18 to Sep 8 — about 1.7 months when the water holds above 68°F.

30°40°50°60°70°80°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmcomfortable to swim
Sea temperature (°F)Comfort
Jan38Bracing
Feb36Bracing
Mar36Bracing
Apr38Bracing
May43Bracing
Jun55Bracing
Jul68Refreshing
Aug71Refreshing
Sep67Cool
Oct57Bracing
Nov47Bracing
Dec42Bracing

UV index in Zion in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 6 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Zion 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 1 (low).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJun 22UV 9Jan 1UV 1
UV index (midday)Level
Jan1Low
Feb2Moderate
Mar4Moderate
Apr6High
May7Very high
Jun9Very high
Jul9Very high
Aug8Very high
Sep6High
Oct3Moderate
Nov2Moderate
Dec1Low

Air quality in Zion 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 Zion is worst in July — around 17 µg/m³ PM2.5 (moderate), about 1.8× the cleanest month (October, 9 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1017 µg/m³Oct 249 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb13Moderate
Mar15Moderate
Apr15Moderate
May16Moderate
Jun17Moderate
Jul17Moderate
Aug16Moderate
Sep13Moderate
Oct9Good
Nov9Good
Dec10Good
Location & terrain

Where is Zion?

Zion sits at 42.4°N, 87.8°W, 650 ft above sea level, in United States. The nearest listed city is Waukegan, 5.6 mi away.

Topography around Zion

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

Within 2 miles, the terrain around Zion has only modest variations in elevation — a maximum elevation change of 233 ft around an average of 650 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 295 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 804 ft.

The land around Zion is covered by trees (47%), grassland (24%) and artificial surfaces (20%) within 2 miles, water (44%) and trees (20%) within 10 miles, and water (47%) within 50 miles.

2 miles
233 ft
10 miles
295 ft
50 miles
804 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Waukegan 5.6 mi · Gurnee 6.2 mi · North Chicago 8.1 mi · Pleasant Prairie 8.7 mi · Kenosha 9.3 mi · Grayslake 13 mi · Libertyville 13 mi · Lake Forest 13 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 Zion (42.4461°, -87.8328°, elevation 650 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. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. 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).