Stillwater weather in September

In September, Stillwater sees average daytime highs of 71°F and overnight lows near 52°F, with 3.4 in of rain across 9.4 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 76°F in the first days to 65°F by the end. The sky is clear or mostly clear about 38% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 06 min at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Stillwater's 3rd-clearest and 6th-windiest month. For the whole year in context, see Stillwater's year-round climate.

Daytime high
71°
4th warmest
Overnight low
52°
9th coldest
Rainfall
3.4 in
9.4 wet days
Daylight
12 h 18 min
5:56 AM – 6:15 PM
Cloud cover
53%
3rd clearest
Wind
8 mph
6th windiest
Solar energy
4.16 kWh/m²
Travel score
6.7
out of 10

Stillwater is city in and county seat of Washington County, Minnesota, United States.

Density
915/km²
people per km²
Founded
1843

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 76°F in the first days to 65°F by the end.

A typical September day in Stillwater reaches about 71°F in the afternoon and slips back to 52°F overnight — a 18°F spread between the day's warmth and the night's chill. On most days the high lands between 59°F and 82°F. Set against its neighbours, September runs about 8°F cooler than August and about 14°F warmer than October.

40°60°80°151015202530
Avg high (°F)Avg low (°F)
17658
27658
37657
47557
57557
67456
77456
87455
97355
107355
117354
127254
137254
147153
157153
167052
177052
186952
196951
206951
216850
226850
236749
246749
256648
266648
276547
286547
296547
306446

How September really feels in Stillwater

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.

Stillwater 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
Jan23° / 1.06690.0
Feb28° / 11°1.05.24.910.10.0
Mar40° / 24°2.07.84.311.60.4
Apr55° / 37°3.210.72.513.23.4
May67° / 49°4.312.20.114.65.8
Jun77° / 59°4.412015.46.4
Jul81° / 63°3.410.3015.16.6
Aug78° / 61°3.810.1013.96.8
Sep71° / 52°3.49.4012.36.7
Oct56° / 40°2.79.10.810.73.9
Nov40° / 27°2.06.73.79.30.4
Dec27° / 14°1.46.46.28.60.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 38% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 16% of September, with mostly cloudy or overcast conditions the remaining 46%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16139
26040
36040
46040
56040
65941
75941
85842
95842
105644
115545
125446
135446
145347
155248
165149
175050
185050
195050
204951
214951
225050
235050
245050
255050
265050
275050
285050
295050
305050

Chance of precipitation in September

Any precipitation

Stillwater gets around 3.4 in of rain over 9.4 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 31% and peaks near 34% on the wettest days.

0%10%20%30%40%151015202530
Rain chance (%)
130
230
330
430
530
630
730
830
930
1030
1130
1230
1330
1430
1530
1630
1731
1831
1931
2032
2132
2232
2333
2433
2533
2633
2734
2834
2933
3033

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 63% of days. Sticky, muggy-or-worse air turns up on roughly 7% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
1392322142
2412321132
3432320122
4452219121
5472218111
6492217111
7512117101
853211691
953211691
1055211581
1155211581
1257211471
1358211471
1459211361
1562201260
1663201250
1764201150
1866191140
1967191040
206918940
217118830
227317730
237416730
247715620
257815520
267914520
278113420
288212420
298610310
30879310

Wind in September

Winds average 8 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.

051015151015202530
Wind speed (mph)Feels
17calm
27calm
37light breeze
47light 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
198light breeze
208light breeze
218light 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 13 h 06 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 90 minutes over September. Sunrise moves from 5:38 AM to 6:14 AM, and sunset from 6:44 PM to 5:47 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.15:386:44
213.15:396:42
313.05:406:40
412.95:416:38
512.95:436:36
612.85:446:35
712.85:456:33
812.75:466:31
912.75:486:29
1012.65:496:27
1112.65:506:25
1212.55:516:23
1312.55:536:21
1412.45:546:19
1512.45:556:17
1612.35:566:15
1712.35:576:13
1812.25:596:11
1912.16:006:09
2012.16:016:07
2112.06:026:05
2212.06:046:03
2311.96:056:01
2411.96:065:59
2511.86:085:57
2611.86:095:55
2711.76:105:53
2811.76:115:51
2911.66:135:49
3011.66:145:47

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.16 kWh/m².

For context, solar energy here swings from a low near 1.39 kWh/m² to a high of 6.27 kWh/m² in July across the year — September's 4.16 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.9Bright
24.8Bright
34.8Bright
44.7Bright
54.7Bright
64.6Bright
74.6Bright
84.5Bright
94.5Bright
104.4Bright
114.3Bright
124.3Bright
134.2Bright
144.2Bright
154.1Bright
164.1Bright
174.0Bright
184.0Moderate
193.9Moderate
203.9Moderate
213.8Moderate
223.8Moderate
233.8Moderate
243.7Moderate
253.7Moderate
263.6Moderate
273.6Moderate
283.6Moderate
293.5Moderate
303.5Moderate
Planning a trip in September

Is September a good time to visit Stillwater?

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

6.7
Sightseeing
2nd-best month of the year
4.3
Beach & pool
4th-best month of the year

September is a reasonable time to visit Stillwater for sightseeing.

What to pack for Stillwater in September

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

In September, Stillwater sees daytime highs around 71°F and nights near 52°F. Worth packing: rain gear. About 9 days see rain.

rain gear

UV index in Stillwater in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 5 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Stillwater peaks around June 18 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 12 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 18UV 8Jan 12UV 1
UV index (midday)Level
Jan1Low
Feb2Low
Mar3Moderate
Apr5Moderate
May7High
Jun9Very high
Jul8Very high
Aug7Very high
Sep5High
Oct3Moderate
Nov2Low
Dec1Low
Location & terrain

Where is Stillwater?

Stillwater sits at 45.1°N, 92.8°W, 696 ft above sea level, in United States. The nearest listed city is Oakdale, 9.9 mi away.

Topography around Stillwater

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

Within 2 miles, the terrain around Stillwater has only modest variations in elevation — a maximum elevation change of 312 ft around an average of 850 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 463 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 830 ft.

The land around Stillwater is covered by trees (46%) within 2 miles, trees (49%) and grassland (27%) within 10 miles, and trees (43%) and cropland (32%) within 50 miles.

2 miles
312 ft
10 miles
463 ft
50 miles
830 ft
treesgrasslandcroplandartificial surfaceswaterwetland
September weather nearby: Oakdale 9.9 mi · White Bear Lake 9.9 mi · Maplewood 12 mi · Woodbury 12 mi · Lino Lakes 16 mi · South Saint Paul 16 mi · Saint Paul 16 mi · River Falls 16 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 Stillwater (45.0564°, -92.806°, elevation 696 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. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).