Chamonix weather in September

In September, Chamonix sees average daytime highs of 14°C and overnight lows near 4°C, with 123 mm of precipitation across 15.1 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 11th-wettest month of the year here.

Highs ease over the month, from about 15°C in the first days to 12°C by the end. The sky is clear or mostly clear about 27% 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 30 min by month's end. Set against the rest of the year, September is Chamonix's 6th-clearest and 10th-windiest month. For the whole year in context, see Chamonix's year-round climate.

Daytime high
14°
4th warmest
Overnight low
9th coldest
Precipitation
123 mm
15.1 wet days
Daylight
12 h 18 min
6:17 AM – 6:36 PM
Cloud cover
60%
6th clearest
Wind
4 km/h
10th windiest
Solar energy
3.98 kWh/m²
Travel score
3.5
out of 10

Chamonix is commune in Haute-Savoie, France.

Density
91/km²
people per km²
Founded
1091

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 15°C in the first days to 12°C by the end.

A typical September day in Chamonix reaches about 14°C in the afternoon and slips back to 4°C overnight — a 10°C spread between the day's warmth and the night's chill. On most days the high lands between 8°C and 19°C. Set against its neighbours, September runs about 4°C cooler than August and about 4°C warmer than October.

10°20°151015202530
Avg high (°C)Avg low (°C)
1166
2166
3166
4155
5155
6155
7155
8155
9155
10145
11144
12144
13144
14144
15144
16144
17134
18134
19133
20133
21133
22133
23133
24133
25123
26123
27123
28122
29122
30122

How September really feels in Chamonix

Once humidity and wind are folded in, September averages 0 days that feel above 32°C and 0 that feel at or below 0°C — the comfort signal a plain temperature reading hides.

Days feeling ≥ 32°C
0
heat index over the day's high
Days feeling ≤ C
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.

Chamonix weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 11th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan-3° / -11°17413.613.98.90.0
Feb-1° / -10°14411.912.3100.0
Mar / -6°14213.913.211.60.0
Apr / -3°12415.410.313.30.7
May12° / 18220.15.714.72.3
Jun16° / 16319.4115.53.8
Jul18° / 16719.10.515.24.7
Aug17° / 15717.80.3144.7
Sep14° / 12315.12.112.33.5
Oct10° / 12112.74.810.72.0
Nov / -6°14613.711.59.30.1
Dec-2° / -10°17814148.50.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 27% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 18% of September, with mostly cloudy or overcast conditions the remaining 56%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14852
24753
34753
44852
54951
64852
74951
84951
94852
104852
114852
124852
134654
144654
154654
164456
174456
184357
194258
204159
214159
224159
234258
244159
254159
264159
274159
284159
294060
304060

Chance of precipitation in September

Any precipitationSnow

Chamonix gets around 123 mm of rain and snow over 15.1 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 51% and peaks near 53% on the wettest days, and about 2 days bring snow.

0%20%40%60%151015202530
Rain chance (%)Snow chance (%)
1523
2513
3513
4523
5524
6524
7524
8525
9535
10535
11536
12536
13536
14537
15537
16538
17538
18528
19529
20519
21509
22509
23499
244910
254810
264810
274810
284810
294711
304711

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 (%)
1100
2100
3100
4100
5100
6100
7100
8100
9100
10100
11100
12100
13100
14100
15100
16100
17100
18100
19100
20100
21100
22100
23100
24100
25100
26100
27100
28100
29100
30100

Wind in September

Winds average 4 km/h in September.

Across September, daily wind ranges from about 4 km/h on the calmest days to 4 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
14calm
24calm
34calm
44calm
54calm
64calm
74calm
84calm
94calm
104calm
114calm
124calm
134calm
144calm
154calm
164calm
174calm
184calm
194calm
204calm
214calm
224calm
234calm
244calm
254calm
264calm
274calm
284calm
294calm
304calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 06 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 96 minutes over September. Sunrise moves from 5:58 AM to 6:36 AM, and sunset from 7:06 PM to 6:08 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.15:587:06
213.15:597:04
313.06:017:03
413.06:027:01
512.96:036:59
612.96:046:57
712.86:066:55
812.86:076:53
912.76:086:51
1012.76:106:49
1112.66:116:47
1212.56:126:45
1312.56:136:43
1412.46:156:40
1512.46:166:38
1612.36:176:36
1712.36:196:34
1812.26:206:32
1912.26:216:30
2012.16:226:28
2112.06:246:26
2212.06:256:24
2311.96:266:22
2411.96:286:20
2511.86:296:18
2611.86:306:16
2711.76:326:14
2811.76:336:12
2911.66:346:10
3011.56:366:08

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.98 kWh/m².

For context, solar energy here swings from a low near 1.37 kWh/m² to a high of 5.84 kWh/m² in June across the year — September's 3.98 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.5Bright
24.5Bright
34.5Bright
44.4Bright
54.4Bright
64.3Bright
74.3Bright
84.3Bright
94.2Bright
104.2Bright
114.1Bright
124.1Bright
134.1Bright
144.0Bright
154.0Moderate
164.0Moderate
173.9Moderate
183.9Moderate
193.8Moderate
203.8Moderate
213.8Moderate
223.7Moderate
233.7Moderate
243.6Moderate
253.6Moderate
263.6Moderate
273.5Moderate
283.5Moderate
293.4Moderate
303.4Moderate
Planning a trip in September

Is September a good time to visit Chamonix?

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

3.5
Sightseeing
4th-best month of the year
0.1
Beach & pool
4th-best month of the year

September is a weaker month for outdoor sightseeing in Chamonix.

What to pack for Chamonix in September

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

In September, Chamonix sees daytime highs around 14°C and nights near 4°C. Pack rain gear. Worth having: a warm layer. About 15 days see rain.

rain geara warm layer

UV index in Chamonix 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 Chamonix peaks around July 13 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 highHighModerateLowJul 13UV 9Jan 1UV 1
UV index (midday)Level
Jan1Low
Feb3Moderate
Mar5Moderate
Apr5High
May7Very high
Jun9Very high
Jul9Very high
Aug8Very high
Sep6High
Oct4Moderate
Nov2Low
Dec1Low
Location & terrain

Where is Chamonix?

Chamonix sits at 45.9°N, 6.9°E, 0 m above sea level, in France. The nearest listed city is Sallanches, 19 km away.

Topography around Chamonix

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Chamonix.

Within 3 km, the terrain around Chamonix has very significant variations in elevation — a maximum elevation change of 1,463 m around an average of 1,562 m above sea level; within 16 km, extreme variations in elevation — a maximum elevation change of 4,245 m; within 80 km, extreme variations in elevation — a maximum elevation change of 4,495 m.

The land around Chamonix is covered by trees (61%) and grassland (25%) within 3 km, trees (28%), grassland (26%) and snow and ice (24%) within 16 km, and trees (41%) and grassland (34%) within 80 km.

3 km
1,463 m
16 km
4,245 m
80 km
4,495 m
treesgrasslandcroplandartificial surfacesbare terrainsnow and icewatermoss and lichen
September weather nearby: Sallanches 19 km · Martigny-Ville 25 km · Cluses 27 km · Monthey 37 km · Aosta 40 km · Albertville 46 km · Sitten 50 km · Annecy-le-Vieux 56 km

France travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type C / E
230 V · 50 Hz
Prices
≈ 77% of US
price level, 2025
GDP per capita
$48,986
2025
Happiness
6.6 / 10
World Happiness, 2025
Safe drinking water
100%
of population, 2024
Homicide rate
1.3
per 100k, 2023
Road deaths
5.1
per 100k/yr, 2019
Income group
High
World Bank
English
Moderate
EF EPI 539
Religion
Roman Catholic 47%none 33%Muslim 4%Protestant 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 Chamonix (45.9237°, 6.8693°, elevation 0 m), 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).