Ames weather in September

In September, Ames sees average daytime highs of 74°F and overnight lows near 54°F, with 3.6 in of rain across 8.5 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 6th-wettest month of the year here.

Highs ease over the month, from about 79°F in the first days to 70°F by the end. The sky is clear or mostly clear about 47% 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 Ames's 1st-clearest and 9th-windiest month. For the whole year in context, see Ames's year-round climate.

Daytime high
74°
4th warmest
Overnight low
54°
9th coldest
Rainfall
3.6 in
8.5 wet days
Daylight
12 h 18 min
6:00 AM – 6:17 PM
Cloud cover
46%
1st clearest
Wind
9 mph
9th windiest
Solar energy
4.6 kWh/m²
Travel score
7.2
out of 10

Ames is city in Story County, Iowa, United States.

Density
1,035/km²
people per km²
Founded
1864

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 79°F in the first days to 70°F by the end.

A typical September day in Ames 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)
18060
27960
37959
47959
57858
67858
77858
87757
97757
107756
117656
127656
137555
147555
157554
167454
177454
187453
197353
207352
217352
227251
237251
247151
257150
267150
277049
287049
296949
306948

How September really feels in Ames

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.

Ames weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan28° / 13°1.264.89.30.0
Feb33° / 16°1.46.54.710.30.0
Mar47° / 28°2.58.9311.71.5
Apr60° / 40°4.511.1113.14.6
May71° / 52°5.513.60.114.36.0
Jun80° / 62°5.111.80156.3
Jul83° / 65°3.89.6014.76.1
Aug81° / 62°4.09.2013.76.8
Sep74° / 54°3.68.5012.37.2
Oct62° / 42°2.980.510.95.5
Nov47° / 29°2.06.51.79.61.6
Dec33° / 18°1.664.590.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 47% 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 40%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16634
26634
36634
46634
56535
66436
76337
86337
96238
106139
116139
125941
135941
145842
155743
165743
175644
185644
195743
205743
215743
225743
235842
245842
255941
265941
275941
286040
296040
306040

Chance of precipitation in September

Any precipitation

Ames gets around 3.6 in of rain over 8.5 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 32% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
126
226
326
426
526
626
727
827
928
1029
1129
1230
1330
1431
1531
1631
1732
1832
1931
2031
2131
2230
2330
2430
2529
2629
2729
2828
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 (%)
1252223227
2272223217
3292322196
4312322186
5332321175
6362321165
7382320154
8392319144
9412319133
10432318133
11452317133
12472217122
13482216122
14502216112
15522115111
16542114101
17552014101
18562013101
1959191291
2060191191
2163181180
2265171080
236717970
246916960
257115860
267215850
277414750
287613740
297613740
307912630

Wind in September

Winds average 9 mph in September.

Across September, daily wind ranges from about 8 mph on the calmest days to 10 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
99light breeze
109light breeze
119light breeze
129light breeze
139light breeze
149light breeze
159light breeze
169light breeze
179light breeze
189light breeze
199light breeze
209light breeze
219light breeze
229light breeze
239light breeze
249light breeze
259light breeze
269light breeze
279light breeze
289light breeze
299light breeze
3010light 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 5:44 AM to 6:16 AM, and sunset from 6:44 PM to 5:52 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.05:446:44
212.95:456:42
312.95:466:41
412.95:486:39
512.85:496:37
612.85:506:35
712.75:516:33
812.75:526:32
912.65:536:30
1012.65:546:28
1112.55:556:26
1212.55:566:24
1312.45:576:23
1412.45:586:21
1512.35:596:19
1612.36:006:17
1712.26:026:15
1812.26:036:14
1912.16:046:12
2012.16:056:10
2112.06:066:08
2212.06:076:06
2311.96:086:04
2411.96:096:03
2511.86:106:01
2611.86:115:59
2711.76:125:57
2811.76:145:55
2911.66:155:54
3011.66:165:52

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.6 kWh/m².

For context, solar energy here swings from a low near 1.77 kWh/m² to a high of 6.46 kWh/m² in July across the year — September's 4.6 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.2Bright
25.2Bright
35.2Bright
45.1Bright
55.1Bright
65.0Bright
75.0Bright
84.9Bright
94.9Bright
104.8Bright
114.8Bright
124.7Bright
134.7Bright
144.6Bright
154.6Bright
164.5Bright
174.5Bright
184.4Bright
194.4Bright
204.3Bright
214.3Bright
224.2Bright
234.2Bright
244.2Bright
254.1Bright
264.1Bright
274.0Bright
284.0Bright
294.0Moderate
303.9Moderate
Planning a trip in September

Is September a good time to visit Ames?

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

7.2
Sightseeing
1st-best month of the year
5.7
Beach & pool
4th-best month of the year

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

What to pack for Ames in September

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

In September, Ames sees daytime highs around 74°F and nights near 54°F. Worth packing: light clothes, rain gear and sun protection. About 9 days see rain.

light clothesrain gearsun protection

UV index in Ames 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 Ames 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 highHighModerateLowJun 19UV 9Dec 21UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar4Moderate
Apr6High
May7High
Jun9Very high
Jul8Very high
Aug7Very high
Sep6High
Oct4Moderate
Nov3Moderate
Dec2Low

Air quality in Ames 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 Ames 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).

01020JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateGoodJul 2016 µg/m³Oct 217 µg/m³
PM2.5 (µg/m³)Level
Jan13Moderate
Feb15Moderate
Mar14Moderate
Apr11Good
May11Good
Jun12Moderate
Jul16Moderate
Aug14Moderate
Sep12Good
Oct7Good
Nov9Good
Dec10Good
Location & terrain

Where is Ames?

Ames sits at 42.0°N, 93.6°W, 942 ft above sea level, in United States. The nearest listed city is Ankeny, 21 mi away.

Topography around Ames

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

Within 2 miles, the terrain around Ames has only modest variations in elevation — a maximum elevation change of 207 ft around an average of 932 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 325 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 568 ft.

The land around Ames is covered by trees (38%) and artificial surfaces (34%) within 2 miles, cropland (74%) within 10 miles, and cropland (78%) within 50 miles.

2 miles
207 ft
10 miles
325 ft
50 miles
568 ft
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Ankeny 21 mi · Johnston 25 mi · Altoona 28 mi · Urbandale 29 mi · Des Moines 30 mi · Clive 30 mi · West Des Moines 32 mi · Waukee 32 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 Ames (42.0347°, -93.6199°, elevation 942 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).