Voiron weather in September

In September, Voiron sees average daytime highs of 20°C and overnight lows near 11°C, with 103 mm of rain across 10.6 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 8th-wettest month of the year here.

Highs ease over the month, from about 22°C in the first days to 19°C by the end. The sky is clear or mostly clear about 34% 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 Voiron's 4th-clearest and 8th-windiest month. For the whole year in context, see Voiron's year-round climate.

Daytime high
20°
4th warmest
Overnight low
11°
9th coldest
Rainfall
103 mm
10.6 wet days
Daylight
12 h 18 min
6:23 AM – 6:41 PM
Cloud cover
55%
4th clearest
Wind
6 km/h
8th windiest
Solar energy
3.95 kWh/m²
Travel score
6.3
out of 10
Air quality
Excellent
PM10 15 µg/m³ · 2019

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 22°C in the first days to 19°C by the end.

A typical September day in Voiron reaches about 20°C in the afternoon and slips back to 11°C overnight — a 10°C spread between the day's warmth and the night's chill. On most days the high lands between 15°C and 26°C. Set against its neighbours, September runs about 4°C cooler than August and about 5°C warmer than October.

10°15°20°25°30°151015202530
Avg high (°C)Avg low (°C)
12313
22312
32212
42212
52212
62212
72212
82212
92111
102111
112111
122111
132111
142111
152111
162011
172011
182010
192010
202010
212010
221910
231910
241910
251910
261910
27199
28199
29189
30189

How September really feels in Voiron

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.

Voiron 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 / -2°10512.86.48.90.3
Feb / -1°9211.35.710.10.9
Mar12° / 9612.43.711.62.9
Apr15° / 11213.62.113.24.1
May19° / 13315.30.314.65.3
Jun23° / 13°10813.2015.46.3
Jul25° / 15°9710.9015.17.0
Aug25° / 14°9410.7013.97.0
Sep20° / 11°10310.6012.36.3
Oct16° / 11111.50.310.74.7
Nov10° / 13213.13.39.32.0
Dec / -1°11613.168.60.5

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 34% 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 47%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16139
26139
36040
46040
56040
66040
76040
85941
95941
105842
115743
125644
135644
145446
155347
165248
175149
185050
194951
204852
214753
224852
234753
244654
254654
264654
274555
284357
294357
304258

Chance of precipitation in September

Any precipitation

Voiron gets around 103 mm of rain over 10.6 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 36% and peaks near 41% on the wettest days. The odds climb toward the end of the month.

0%10%20%30%40%50%151015202530
Rain chance (%)
131
231
331
432
532
632
732
833
933
1034
1134
1235
1336
1436
1537
1637
1737
1838
1938
2038
2138
2238
2339
2439
2539
2639
2740
2840
2940
3041

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 73% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)
1553681
2583570
3583570
4603460
5623350
6623350
7643240
8643240
9663130
10663130
11683020
12683020
13702910
14712810
15722710
16732610
17752500
18762400
19782200
20792100
21811900
22821800
23831700
24841600
25851500
26861400
27871300
28881200
29891100
30901000

Wind in September

Winds average 6 km/h in September.

Across September, daily wind ranges from about 6 km/h on the calmest days to 6 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
16calm
26calm
36calm
46calm
56calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm

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 6:04 AM to 6:40 AM, and sunset from 7:11 PM to 6:14 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.16:047:11
213.16:057:09
313.06:067:07
413.06:087:05
512.96:097:03
612.96:107:01
712.86:116:59
812.76:136:57
912.76:146:55
1012.66:156:53
1112.66:166:51
1212.56:186:49
1312.56:196:47
1412.46:206:45
1512.46:216:43
1612.36:236:41
1712.36:246:39
1812.26:256:37
1912.16:266:35
2012.16:286:33
2112.06:296:31
2212.06:306:29
2311.96:316:27
2411.96:336:25
2511.86:346:23
2611.86:356:21
2711.76:376:19
2811.76:386:17
2911.66:396:15
3011.66:406:14

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.95 kWh/m².

For context, solar energy here swings from a low near 1.21 kWh/m² to a high of 6.23 kWh/m² in July across the year — September's 3.95 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.7Bright
24.7Bright
34.6Bright
44.6Bright
54.5Bright
64.5Bright
74.4Bright
84.4Bright
94.3Bright
104.3Bright
114.2Bright
124.1Bright
134.1Bright
144.0Bright
154.0Moderate
163.9Moderate
173.9Moderate
183.8Moderate
193.8Moderate
203.7Moderate
213.6Moderate
223.6Moderate
233.5Moderate
243.5Moderate
253.4Moderate
263.4Moderate
273.4Moderate
283.3Moderate
293.3Moderate
303.2Moderate
Planning a trip in September

Is September a good time to visit Voiron?

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

6.3
Sightseeing
3rd-best month of the year
3.6
Beach & pool
4th-best month of the year

September is a reasonable time to visit Voiron for sightseeing.

What to pack for Voiron in September

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

In September, Voiron sees daytime highs around 20°C and nights near 11°C. Worth packing: rain gear. About 11 days see rain.

rain gear

UV index in Voiron 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 Voiron peaks around July 16 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 16UV 9Dec 22UV 1
UV index (midday)Level
Jan1Low
Feb3Moderate
Mar4Moderate
Apr5High
May7High
Jun7Very high
Jul9Very high
Aug7High
Sep5High
Oct4Moderate
Nov2Low
Dec1Low

Air quality in Voiron 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 Voiron is worst in March — around 17 µg/m³ PM2.5 (moderate), and holds fairly steady the rest of the year.

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

01020JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateMar 2117 µg/m³Aug 1312 µg/m³
PM2.5 (µg/m³)Level
Jan16Moderate
Feb15Moderate
Mar17Moderate
Apr17Moderate
May14Moderate
Jun16Moderate
Jul12Good
Aug12Good
Sep12Moderate
Oct13Moderate
Nov13Moderate
Dec15Moderate
Location & terrain

Where is Voiron?

Voiron sits at 45.4°N, 5.6°E, 301 m above sea level, in France. The nearest listed city is Saint-Égrève, 16 km away.

Topography around Voiron

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

Within 3 km, the terrain around Voiron has significant variations in elevation — a maximum elevation change of 580 m around an average of 383 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,724 m; within 80 km, extreme variations in elevation — a maximum elevation change of 3,838 m.

The land around Voiron is covered by trees (47%), grassland (26%) and artificial surfaces (20%) within 3 km, trees (56%) and grassland (25%) within 16 km, and trees (52%) and grassland (26%) within 80 km.

3 km
580 m
16 km
1,724 m
80 km
3,838 m
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Saint-Égrève 16 km · Fontaine 21 km · Meylan 23 km · Grenoble 23 km · Saint-Martin-d'Hères 25 km · Échirolles 26 km · Chambéry 34 km · Villefontaine 44 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 Voiron (45.3647°, 5.5856°, elevation 301 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. 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).