Thonon-les-Bains weather in September

In September, Thonon-les-Bains sees average daytime highs of 18°C and overnight lows near 9°C, with 115 mm of precipitation across 13.1 wet days and about 12.4 hours of daylight. It is the 4th-warmest and 8th-wettest month of the year here.

Highs ease over the month, from about 19°C in the first days to 16°C by the end. The sky is clear or mostly clear about 31% 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 Thonon-les-Bains's 3rd-clearest and 10th-windiest month. For the whole year in context, see Thonon-les-Bains's year-round climate.

Daytime high
18°
4th warmest
Overnight low
9th coldest
Precipitation
115 mm
13.1 wet days
Daylight
12 h 18 min
6:19 AM – 6:38 PM
Cloud cover
56%
3rd clearest
Wind
5 km/h
10th windiest
Solar energy
3.84 kWh/m²
Travel score
5.3
out of 10
Air quality
Good
PM10 19.5 µg/m³ · 2010

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 19°C in the first days to 16°C by the end.

A typical September day in Thonon-les-Bains reaches about 18°C in the afternoon and slips back to 9°C overnight — a 9°C spread between the day's warmth and the night's chill. On most days the high lands between 12°C and 22°C. Set against its neighbours, September runs about 4°C cooler than August and about 4°C warmer than October.

10°15°20°25°151015202530
Avg high (°C)Avg low (°C)
12010
21910
31910
41910
51910
61910
7199
8199
9189
10189
11189
12189
13189
14189
15189
16188
17178
18178
19178
20178
21178
22178
23178
24168
25167
26167
27167
28167
29167
30167

How September really feels in Thonon-les-Bains

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.

Thonon-les-Bains weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 8th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / -4°11612.310.28.80.0
Feb / -4°10111.19.4100.0
Mar / -1°10912.9811.61.5
Apr12° / 11314.45.413.32.9
May16° / 16117.71.314.74.2
Jun20° / 10°14616.20.115.55.4
Jul22° / 12°14615.4015.26.0
Aug22° / 12°13614.40146.1
Sep18° / 11513.10.212.45.3
Oct13° / 11112.7210.73.5
Nov / 12313.36.69.21.0
Dec / -3°13213.29.88.50.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 31% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 19% of September, with mostly cloudy or overcast conditions the remaining 50%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15644
25644
35644
45644
55644
65644
75644
85545
95545
105446
115446
125347
135248
145248
155149
165050
174951
184852
194753
204654
214654
224555
234555
244555
254456
264456
274456
284258
294258
304159

Chance of precipitation in September

Any precipitationSnow

Thonon-les-Bains gets around 115 mm of rain and snow over 13.1 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 44% and peaks near 46% on the wettest days, and about 0 day brings snow.

0%20%40%60%151015202530
Rain chance (%)Snow chance (%)
1430
2430
3430
4430
5420
6420
7420
8430
9430
10431
11431
12431
13441
14441
15441
16441
17451
18451
19451
20451
21451
22451
23451
24451
25451
26452
27462
28462
29462
30462

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 91% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
173261
275241
377221
479210
580200
682180
783170
885150
986140
1088120
1189110
1290100
139190
149280
159370
169460
179550
189640
199640
209730
219820
229820
239820
249910
259910
269910
279910
289910
299910
309910

Wind in September

Winds average 5 km/h in September.

Across September, daily wind ranges from about 5 km/h on the calmest days to 5 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
15calm
25calm
35calm
45calm
55calm
65calm
75calm
85calm
95calm
105calm
115calm
125calm
135calm
145calm
155calm
165calm
175calm
185calm
195calm
205calm
215calm
225calm
235calm
245calm
255calm
265calm
275calm
285calm
295calm
305calm

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 5:59 AM to 6:37 AM, and sunset from 7:09 PM to 6:09 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.25:597:09
213.16:007:07
313.06:027:05
413.06:037:03
512.96:047:01
612.96:066:59
712.86:076:57
812.86:086:55
912.76:096:52
1012.76:116:50
1112.66:126:48
1212.56:136:46
1312.56:156:44
1412.46:166:42
1512.46:176:40
1612.36:196:38
1712.36:206:36
1812.26:216:34
1912.26:236:32
2012.16:246:30
2112.06:256:28
2212.06:276:26
2311.96:286:24
2411.96:296:22
2511.86:316:20
2611.86:326:18
2711.76:336:16
2811.66:356:13
2911.66:366:11
3011.56:376:09

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.84 kWh/m².

For context, solar energy here swings from a low near 1.17 kWh/m² to a high of 5.79 kWh/m² in June across the year — September's 3.84 kWh/m² falls in the middle.

012345151015202530
Solar energy (kWh/m²)Level
14.5Bright
24.4Bright
34.4Bright
44.4Bright
54.3Bright
64.3Bright
74.2Bright
84.2Bright
94.1Bright
104.1Bright
114.0Bright
124.0Bright
134.0Moderate
143.9Moderate
153.9Moderate
163.8Moderate
173.8Moderate
183.7Moderate
193.7Moderate
203.6Moderate
213.6Moderate
223.5Moderate
233.5Moderate
243.4Moderate
253.4Moderate
263.3Moderate
273.3Moderate
283.3Moderate
293.2Moderate
303.2Moderate
Planning a trip in September

Is September a good time to visit Thonon-les-Bains?

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

5.3
Sightseeing
4th-best month of the year
1.6
Beach & pool
4th-best month of the year

September is a reasonable time to visit Thonon-les-Bains for sightseeing.

What to pack for Thonon-les-Bains in September

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

In September, Thonon-les-Bains sees daytime highs around 18°C and nights near 9°C. Worth packing: rain gear. About 13 days see rain.

rain gear

UV index in Thonon-les-Bains 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 Thonon-les-Bains peaks around July 15 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 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 15UV 9Dec 22UV 1
UV index (midday)Level
Jan1Low
Feb2Moderate
Mar4Moderate
Apr5High
May7High
Jun7Very high
Jul9Very high
Aug7High
Sep5Moderate
Oct3Moderate
Nov2Low
Dec1Low
Location & terrain

Where is Thonon-les-Bains?

Thonon-les-Bains sits at 46.4°N, 6.5°E, 436 m above sea level, in France. The nearest listed city is Morges, 16 km away.

Topography around Thonon-les-Bains

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Thonon-les-Bains.

Within 3 km, the terrain around Thonon-les-Bains has significant variations in elevation — a maximum elevation change of 272 m around an average of 438 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,511 m; within 80 km, extreme variations in elevation — a maximum elevation change of 4,501 m.

The land around Thonon-les-Bains is covered by trees (39%) and water (29%) within 3 km, water (39%) and trees (35%) within 16 km, and trees (50%) and grassland (32%) within 80 km.

3 km
272 m
16 km
1,511 m
80 km
4,501 m
treesgrasslandcroplandartificial surfacesbare terrainsnow and icewater
September weather nearby: Morges 16 km · Nyon 18 km · Lausanne 20 km · Renens 21 km · Pully 21 km · Annemasse 27 km · Vevey 30 km · Geneva 32 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 Thonon-les-Bains (46.3705°, 6.4798°, elevation 436 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).