Kalispell weather in September

In September, Kalispell sees average daytime highs of 66°F and overnight lows near 43°F, with 1.8 in of precipitation across 7.1 wet days and about 12.4 hours of daylight. It is the 4th-warmest and 10th-wettest month of the year here.

Highs ease over the month, from about 72°F in the first days to 61°F by the end. The sky is clear or mostly clear about 43% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 12 min at the start of September to 11 h 30 min by month's end. Set against the rest of the year, September is Kalispell's 3rd-clearest and 7th-windiest month. For the whole year in context, see Kalispell's year-round climate.

Daytime high
66°
4th warmest
Overnight low
43°
9th coldest
Precipitation
1.8 in
7.1 wet days
Daylight
12 h 18 min
6:21 AM – 6:42 PM
Cloud cover
47%
3rd clearest
Wind
3 mph
7th windiest
Solar energy
4.41 kWh/m²
Travel score
6.6
out of 10

Kalispell is seat of Flathead County, Montana, United States.

Density
726/km²
people per km²

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 72°F in the first days to 61°F by the end.

A typical September day in Kalispell reaches about 66°F in the afternoon and slips back to 43°F overnight — a 23°F spread between the day's warmth and the night's chill. On most days the high lands between 54°F and 79°F. Set against its neighbours, September runs about 11°F cooler than August and about 15°F warmer than October.

40°60°80°151015202530
Avg high (°F)Avg low (°F)
17347
27247
37247
47146
57146
67146
77046
87045
96945
106945
116845
126844
136744
146744
156744
166643
176643
186543
196542
206542
216442
226442
236341
246341
256341
266240
276240
286140
296140
306039

How September really feels in Kalispell

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.

Kalispell weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 10th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysSnow daysDaylight (hours)Travel score
Jan29° / 17°2.71414.38.60.0
Feb33° / 18°2.111.211.49.90.0
Mar40° / 23°2.614.210.111.60.2
Apr50° / 30°2.714.15.313.42.1
May60° / 38°3.013.71.214.94.5
Jun67° / 45°3.512.10.415.85.9
Jul77° / 50°1.25.7015.57.8
Aug78° / 50°1.250.114.17.9
Sep66° / 43°1.87.10.112.46.6
Oct51° / 34°2.611.92.810.62.6
Nov38° / 26°3.014.110.690.0
Dec30° / 19°2.713.414.18.20.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 43% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 17% of September, with mostly cloudy or overcast conditions the remaining 40%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16535
26337
36337
46337
56337
66337
76238
86238
96139
106040
115941
126040
135941
145941
155842
165842
175941
185941
195941
205941
215941
225941
235842
245842
255842
265842
275842
285842
295743
305743

Chance of precipitation in September

Any precipitationSnow

Kalispell gets around 1.8 in of rain and snow over 7.1 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 24% and peaks near 26% on the wettest days, and about 0 day brings snow.

0%10%20%30%40%151015202530
Rain chance (%)Snow chance (%)
1180
2190
3200
4200
5210
6220
7220
8230
9240
10250
11250
12260
13260
14260
15260
16260
17250
18250
19250
20250
21250
22250
23251
24251
25251
26241
27242
28252
29252
30252

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 100% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)
1991
2991
3991
4991
5991
6991
7991
8991
9991
10991
11991
12991
13991
14991
151000
161000
171000
181000
191000
201000
211000
221000
231000
241000
251000
261000
271000
281000
291000
301000

Wind in September

Winds average 3 mph in September.

Across September, daily wind ranges from about 3 mph on the calmest days to 3 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
13calm
23calm
33calm
43calm
53calm
63calm
73calm
83calm
93calm
103calm
113calm
123calm
133calm
143calm
153calm
163calm
173calm
183calm
193calm
203calm
213calm
223calm
233calm
243calm
253calm
263calm
273calm
283calm
293calm
303calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 12 min at the start of September to 11 h 30 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 102 minutes over September. Sunrise moves from 6:00 AM to 6:41 AM, and sunset from 7:14 PM to 6:12 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.26:007:14
213.26:017:12
313.16:037:10
413.16:047:08
513.06:067:06
612.96:077:04
712.96:087:01
812.86:106:59
912.86:116:57
1012.76:136:55
1112.66:146:53
1212.66:166:51
1312.56:176:48
1412.56:186:46
1512.46:206:44
1612.36:216:42
1712.36:236:40
1812.26:246:38
1912.26:256:35
2012.16:276:33
2112.06:286:31
2212.06:306:29
2311.96:316:27
2411.96:336:25
2511.86:346:22
2611.76:366:20
2711.76:376:18
2811.66:396:16
2911.66:406:14
3011.56:416:12

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.41 kWh/m².

For context, solar energy here swings from a low near 1.01 kWh/m² to a high of 7.27 kWh/m² in July across the year — September's 4.41 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.3Bright
25.3Bright
35.2Bright
45.1Bright
55.0Bright
65.0Bright
74.9Bright
84.8Bright
94.8Bright
104.7Bright
114.7Bright
124.6Bright
134.5Bright
144.5Bright
154.4Bright
164.3Bright
174.3Bright
184.2Bright
194.2Bright
204.1Bright
214.1Bright
224.0Bright
234.0Moderate
243.9Moderate
253.9Moderate
263.8Moderate
273.8Moderate
283.7Moderate
293.6Moderate
303.6Moderate
Planning a trip in September

Is September a good time to visit Kalispell?

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

6.6
Sightseeing
3rd-best month of the year
3.0
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Kalispell for sightseeing.

What to pack for Kalispell in September

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

In September, Kalispell sees daytime highs around 66°F and nights near 43°F. Worth packing: a warm layer. About 7 days see rain.

a warm layer

UV index in Kalispell in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 4 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Kalispell peaks around July 18 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 18 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 highHighModerateLowJul 18UV 8Dec 18UV 1
UV index (midday)Level
Jan1Low
Feb2Low
Mar4Moderate
Apr5Moderate
May7High
Jun6High
Jul8Very high
Aug7High
Sep4Moderate
Oct3Moderate
Nov1Low
Dec1Low

Air quality in Kalispell 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 Kalispell is worst in August — around 44 µg/m³ PM2.5 (poor), about 10.8× the cleanest month (December, 4 µg/m³).

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

0204060JanFebMarAprMayJunJulAugSepOctNovDecGoodModeratePoorModerateGoodAug 1942 µg/m³Dec 204 µg/m³
PM2.5 (µg/m³)Level
Jan5Good
Feb6Good
Mar8Good
Apr10Good
May10Good
Jun9Good
Jul15Moderate
Aug44Poor
Sep31Moderate
Oct12Good
Nov7Good
Dec4Good
Location & terrain

Where is Kalispell?

Kalispell sits at 48.2°N, 114.3°W, 2,956 ft above sea level, in United States. The nearest listed city is Whitefish, 15 mi away.

Topography around Kalispell

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

Within 2 miles, the terrain around Kalispell has only modest variations in elevation — a maximum elevation change of 804 ft around an average of 2,969 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 2,900 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 7,871 ft.

The land around Kalispell is covered by grassland (36%), trees (30%) and artificial surfaces (29%) within 2 miles, trees (38%), grassland (35%) and cropland (21%) within 10 miles, and trees (73%) within 50 miles.

2 miles
804 ft
10 miles
2,900 ft
50 miles
7,871 ft
treesgrasslandcroplandartificial surfacesbare terrainwatermoss and lichen
September weather nearby: Whitefish 15 mi · Missoula 93 mi · Cranbrook 112 mi · Coeur d'Alene 120 mi · Lethbridge 124 mi · Post Falls 127 mi · Spokane Valley 140 mi · Opportunity 140 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 Kalispell (48.1958°, -114.3129°, elevation 2,956 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).