Marion weather in September

In September, Marion sees average daytime highs of 74°F and overnight lows near 54°F, with 4.0 in of rain across 8.4 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 78°F in the first days to 69°F by the end. The sky is clear or mostly clear about 45% 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 Marion's 1st-clearest and 9th-windiest month. For the whole year in context, see Marion's year-round climate.

Daytime high
74°
4th warmest
Overnight low
54°
9th coldest
Rainfall
4.0 in
8.4 wet days
Daylight
12 h 18 min
5:52 AM – 6:09 PM
Cloud cover
47%
1st clearest
Wind
8 mph
9th windiest
Solar energy
4.53 kWh/m²
Travel score
7.1
out of 10

Marion is city in Linn County, Iowa, United States.

Density
810/km²
people per km²
Founded
1839

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 78°F in the first days to 69°F by the end.

A typical September day in Marion reaches about 74°F in the afternoon and slips back to 54°F overnight — a 20°F spread between the day's warmth and the night's chill. On most days the high lands between 63°F and 85°F. Set against its neighbours, September runs about 6°F cooler than August and about 13°F warmer than October.

40°60°80°151015202530
Avg high (°F)Avg low (°F)
17960
27959
37859
47859
57858
67858
77758
87757
97757
107656
117656
127656
137555
147555
157455
167454
177454
187353
197353
207352
217252
227252
237151
247151
257150
267050
277049
286949
296949
306948

How September really feels in Marion

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.

Marion 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
Jan28° / 13°1.57.15.49.30.0
Feb33° / 17°1.76.44.410.30.0
Mar46° / 28°2.69311.71.4
Apr60° / 40°4.311.80.913.14.4
May70° / 51°4.912.8014.36.0
Jun79° / 62°5.1120156.3
Jul82° / 65°3.89.7014.76.4
Aug80° / 62°3.79.3013.76.8
Sep74° / 54°4.08.4012.37.1
Oct61° / 42°2.98.50.310.95.3
Nov47° / 30°2.37.51.69.61.5
Dec33° / 19°1.96.94.790.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 45% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 14% of September, with mostly cloudy or overcast conditions the remaining 41%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16238
26238
36436
46436
56337
66337
76238
86337
96238
106139
116139
126040
135941
145842
155743
165842
175743
185644
195644
205644
215644
225644
235644
245545
255545
265644
275644
285644
295644
305644

Chance of precipitation in September

Any precipitation

Marion gets around 4.0 in of rain over 8.4 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 29% and peaks near 31% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
126
226
326
426
526
626
726
826
927
1027
1128
1229
1329
1430
1531
1631
1731
1831
1931
2031
2131
2231
2331
2430
2530
2630
2729
2829
2928
3028

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 53% of days. Sticky, muggy-or-worse air turns up on roughly 13% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
1262521217
2282521207
3302521186
4322520176
5342520165
6362520155
7382519144
8402419134
9412418133
10432418123
11452317123
12472317122
13482216112
14502215112
15522115111
16532114111
17562013101
18572012101
1959191291
2060191191
2164181080
2265171080
236717970
246816970
257115860
267115860
277414750
287613740
297613740
307712740

Wind in September

Winds average 8 mph in September.

Across September, daily wind ranges from about 8 mph on the calmest days to 9 mph at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (mph)Feels
18light breeze
28light breeze
38light breeze
48light breeze
58light breeze
68light breeze
78light breeze
88light breeze
98light breeze
108light breeze
118light breeze
128light breeze
138light breeze
148light breeze
158light breeze
168light breeze
178light breeze
188light breeze
199light breeze
209light breeze
219light breeze
229light breeze
239light breeze
249light breeze
259light breeze
269light breeze
279light breeze
289light breeze
299light breeze
309light breeze

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 5:36 AM to 6:08 AM, and sunset from 6:36 PM to 5:44 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.05:366:36
212.95:376:34
312.95:386:32
412.95:396:31
512.85:416:29
612.85:426:27
712.75:436:25
812.75:446:24
912.65:456:22
1012.65:466:20
1112.55:476:18
1212.55:486:16
1312.45:496:15
1412.45:506:13
1512.35:516:11
1612.35:526:09
1712.25:536:07
1812.25:556:05
1912.15:566:04
2012.15:576:02
2112.05:586:00
2212.05:595:58
2311.96:005:56
2411.96:015:54
2511.86:025:53
2611.86:035:51
2711.76:045:49
2811.76:055:47
2911.66:075:46
3011.66:085:44

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.53 kWh/m².

For context, solar energy here swings from a low near 1.73 kWh/m² to a high of 6.39 kWh/m² in July across the year — September's 4.53 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.1Bright
25.1Bright
35.0Bright
45.0Bright
55.0Bright
64.9Bright
74.9Bright
84.8Bright
94.8Bright
104.8Bright
114.7Bright
124.7Bright
134.6Bright
144.5Bright
154.5Bright
164.5Bright
174.4Bright
184.3Bright
194.3Bright
204.3Bright
214.2Bright
224.2Bright
234.1Bright
244.1Bright
254.1Bright
264.0Bright
274.0Moderate
283.9Moderate
293.9Moderate
303.9Moderate
Planning a trip in September

Is September a good time to visit Marion?

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

7.1
Sightseeing
1st-best month of the year
5.6
Beach & pool
4th-best month of the year

September is one of the better times to visit Marion for general sightseeing.

What to pack for Marion in September

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

In September, Marion sees daytime highs around 74°F and nights near 54°F. Worth packing: light clothes, rain gear and sun protection. About 8 days see rain.

light clothesrain gearsun protection

UV index in Marion 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 Marion peaks around June 18 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 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 18UV 9Dec 22UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar4Moderate
Apr6High
May8Very high
Jun9Very high
Jul8Very high
Aug8Very high
Sep6High
Oct3Moderate
Nov2Moderate
Dec2Low

Air quality in Marion 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 Marion is worst in July — around 17 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (October, 8 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateGoodJul 1916 µg/m³Oct 218 µg/m³
PM2.5 (µg/m³)Level
Jan12Moderate
Feb14Moderate
Mar14Moderate
Apr11Good
May13Moderate
Jun13Moderate
Jul17Moderate
Aug15Moderate
Sep12Good
Oct8Good
Nov8Good
Dec10Good
Location & terrain

Where is Marion?

Marion sits at 42.0°N, 91.6°W, 850 ft above sea level, in United States. The nearest listed city is Cedar Rapids, 3.1 mi away.

Topography around Marion

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

Within 2 miles, the terrain around Marion has only modest variations in elevation — a maximum elevation change of 207 ft around an average of 833 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 515 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 738 ft.

The land around Marion is covered by artificial surfaces (41%), grassland (29%) and trees (26%) within 2 miles, cropland (48%) within 10 miles, and cropland (75%) within 50 miles.

2 miles
207 ft
10 miles
515 ft
50 miles
738 ft
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Cedar Rapids 3.1 mi · North Liberty 20 mi · Coralville 25 mi · Iowa City 26 mi · Waterloo 50 mi · Muscatine 51 mi · Cedar Falls 55 mi · Dubuque 58 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 Marion (42.0342°, -91.5977°, elevation 850 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).