Aosta weather in September

In September, Aosta sees average daytime highs of 12°C and overnight lows near 3°C, with 89 mm of precipitation across 12.7 wet days and about 12.3 hours of daylight. It is the 4th-warmest and 9th-wettest month of the year here.

Highs ease over the month, from about 14°C in the first days to 10°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 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 Aosta's 6th-clearest and 11th-windiest month. For the whole year in context, see Aosta's year-round climate.

Daytime high: 12°; 4th warmest
Overnight low: 3°; 9th coldest
Precipitation: 89 mm; 12.7 wet days
Daylight: 12 h 18 min; 6:16 AM – 6:35 PM
Cloud cover: 57%; 6th clearest
Wind: 4 km/h; 11th windiest
Solar energy: 4.07 kWh/m²
Travel score: 2.9; out of 10

Air quality: Moderate; PM2.5 10.5 µg/m³ · 2019

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

← August Aosta year-round climate October →Best places to visit in September

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 14°C in the first days to 10°C by the end.

A typical September day in Aosta reaches about 12°C in the afternoon and slips back to 3°C overnight — a 9°C spread between the day's warmth and the night's chill. On most days the high lands between 6°C and 17°C. Set against its neighbours, September runs about 4°C cooler than August and about 5°C warmer than October.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Avg high (°C)	14	14	14	14	13	13	13	13	13	13	13	12	12	12	12	12	12	11	11	11	11	11	11	10	10	10	10	10	10	9
Avg low (°C)	5	5	4	4	4	4	4	4	4	4	3	3	3	3	3	3	3	3	2	2	2	2	2	2	2	2	1	1	1	1

	Avg high (°C)	Avg low (°C)
1	14	5
2	14	5
3	14	4
4	14	4
5	13	4
6	13	4
7	13	4
8	13	4
9	13	4
10	13	4
11	13	3
12	12	3
13	12	3
14	12	3
15	12	3
16	12	3
17	12	3
18	11	3
19	11	2
20	11	2
21	11	2
22	11	2
23	11	2
24	10	2
25	10	2
26	10	2
27	10	1
28	10	1
29	10	1
30	9	1

How September really feels in Aosta

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

heat index over the day's high

Days feeling ≤ 0°C

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.

Aosta weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 9th-wettest month here — the current month is highlighted below.

Month	High / Low (°C)	Rainfall (mm)	Wet days	Snow days	Daylight (hours)	Travel score
Jan	-6° / -12°	100	11.9	12.8	8.9	0.0
Feb	-4° / -12°	79	10.9	12	10.1	0.0
Mar	0° / -8°	88	12	13.2	11.6	0.0
Apr	3° / -4°	97	13	13.3	13.3	0.0
May	8° / 0°	112	16.3	8.2	14.7	1.1
Jun	13° / 4°	105	16.7	2.3	15.4	3.3
Jul	16° / 7°	95	15.7	0.8	15.1	4.6
Aug	16° / 6°	87	13.9	0.7	13.9	4.6
Sep	12° / 3°	89	12.7	2.9	12.3	2.9
Oct	7° / -1°	98	12.4	7.9	10.7	0.7
Nov	-0° / -7°	124	13.3	13.6	9.3	0.0
Dec	-5° / -11°	110	12.7	13.6	8.5	0.0

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.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Clearer (%)	59	59	59	58	58	57	57	56	56	56	54	54	52	52	50	50	48	47	46	45	45	44	43	43	43	43	43	42	41	41
Cloudier (%)	41	41	41	42	42	43	43	44	44	44	46	46	48	48	50	50	52	53	54	55	55	56	57	57	57	57	57	58	59	59

	Clearer (%)	Cloudier (%)
1	59	41
2	59	41
3	59	41
4	58	42
5	58	42
6	57	43
7	57	43
8	56	44
9	56	44
10	56	44
11	54	46
12	54	46
13	52	48
14	52	48
15	50	50
16	50	50
17	48	52
18	47	53
19	46	54
20	45	55
21	45	55
22	44	56
23	43	57
24	43	57
25	43	57
26	43	57
27	43	57
28	42	58
29	41	59
30	41	59

Chance of precipitation in September

Any precipitationSnow

Aosta gets around 89 mm of rain and snow over 12.7 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 42% and peaks near 44% on the wettest days, and about 3 days bring snow.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Rain chance (%)	42	42	43	43	43	43	43	42	42	42	42	42	42	42	42	42	42	42	42	42	42	42	42	42	43	43	43	43	44	44
Snow chance (%)	6	6	6	6	7	7	7	7	7	8	8	8	8	9	9	10	10	10	11	11	12	12	12	13	14	14	15	16	17	17

	Rain chance (%)	Snow chance (%)
1	42	6
2	42	6
3	43	6
4	43	6
5	43	7
6	43	7
7	43	7
8	42	7
9	42	7
10	42	8
11	42	8
12	42	8
13	42	8
14	42	9
15	42	9
16	42	10
17	42	10
18	42	10
19	42	11
20	42	11
21	42	12
22	42	12
23	42	12
24	42	13
25	43	14
26	43	14
27	43	15
28	43	16
29	44	17
30	44	17

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.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Dry (%)	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100	100

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100

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.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Wind speed (km/h)	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4	4
Feels	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm	calm

	Wind speed (km/h)	Feels
1	4	calm
2	4	calm
3	4	calm
4	4	calm
5	4	calm
6	4	calm
7	4	calm
8	4	calm
9	4	calm
10	4	calm
11	4	calm
12	4	calm
13	4	calm
14	4	calm
15	4	calm
16	4	calm
17	4	calm
18	4	calm
19	4	calm
20	4	calm
21	4	calm
22	4	calm
23	4	calm
24	4	calm
25	4	calm
26	4	calm
27	4	calm
28	4	calm
29	4	calm
30	4	calm

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 5:56 AM to 6:34 AM, and sunset from 7:04 PM to 6:06 PM.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Daylight (h)	13.1	13.1	13.0	13.0	12.9	12.9	12.8	12.8	12.7	12.6	12.6	12.5	12.5	12.4	12.4	12.3	12.3	12.2	12.2	12.1	12.0	12.0	11.9	11.9	11.8	11.8	11.7	11.7	11.6	11.5
Sunrise (AM)	5:56	5:58	5:59	6:00	6:02	6:03	6:04	6:05	6:07	6:08	6:09	6:10	6:12	6:13	6:14	6:16	6:17	6:18	6:19	6:21	6:22	6:23	6:25	6:26	6:27	6:28	6:30	6:31	6:32	6:34
Sunset (PM)	7:04	7:02	7:01	6:59	6:57	6:55	6:53	6:51	6:49	6:47	6:45	6:43	6:41	6:39	6:37	6:35	6:33	6:31	6:28	6:26	6:24	6:22	6:20	6:18	6:16	6:14	6:12	6:10	6:08	6:06

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	13.1	5:56	7:04
2	13.1	5:58	7:02
3	13.0	5:59	7:01
4	13.0	6:00	6:59
5	12.9	6:02	6:57
6	12.9	6:03	6:55
7	12.8	6:04	6:53
8	12.8	6:05	6:51
9	12.7	6:07	6:49
10	12.6	6:08	6:47
11	12.6	6:09	6:45
12	12.5	6:10	6:43
13	12.5	6:12	6:41
14	12.4	6:13	6:39
15	12.4	6:14	6:37
16	12.3	6:16	6:35
17	12.3	6:17	6:33
18	12.2	6:18	6:31
19	12.2	6:19	6:28
20	12.1	6:21	6:26
21	12.0	6:22	6:24
22	12.0	6:23	6:22
23	11.9	6:25	6:20
24	11.9	6:26	6:18
25	11.8	6:27	6:16
26	11.8	6:28	6:14
27	11.7	6:30	6:12
28	11.7	6:31	6:10
29	11.6	6:32	6:08
30	11.5	6:34	6:06

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.07 kWh/m².

For context, solar energy here swings from a low near 1.55 kWh/m² to a high of 6.01 kWh/m² in June across the year — September's 4.07 kWh/m² falls in the middle.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Solar energy (kWh/m²)	4.7	4.7	4.6	4.6	4.5	4.5	4.4	4.4	4.4	4.3	4.3	4.2	4.2	4.1	4.1	4.0	4.0	4.0	3.9	3.9	3.8	3.8	3.7	3.7	3.6	3.6	3.6	3.5	3.5	3.4
Level	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Bright	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate

	Solar energy (kWh/m²)	Level
1	4.7	Bright
2	4.7	Bright
3	4.6	Bright
4	4.6	Bright
5	4.5	Bright
6	4.5	Bright
7	4.4	Bright
8	4.4	Bright
9	4.4	Bright
10	4.3	Bright
11	4.3	Bright
12	4.2	Bright
13	4.2	Bright
14	4.1	Bright
15	4.1	Bright
16	4.0	Bright
17	4.0	Bright
18	4.0	Moderate
19	3.9	Moderate
20	3.9	Moderate
21	3.8	Moderate
22	3.8	Moderate
23	3.7	Moderate
24	3.7	Moderate
25	3.6	Moderate
26	3.6	Moderate
27	3.6	Moderate
28	3.5	Moderate
29	3.5	Moderate
30	3.4	Moderate

Planning a trip in September

Is September a good time to visit Aosta?

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

2.9

Sightseeing

4th-best month of the year

—

Beach & pool

never really warm enough

September is a weaker month for outdoor sightseeing in Aosta.

What to pack for Aosta in September

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

In September, Aosta sees daytime highs around 12°C and nights near 3°C. Pack a warm layer. Worth having: rain gear. About 13 days see rain.

a warm layerrain gear

UV index in Aosta 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 Aosta peaks around July 15 at about 10 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 21 at about 2 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 9 months of the year.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
UV index (midday)	2	3	6	8	9	9	10	8	6	4	2	2
Level	Low	Moderate	High	Very high	Very high	Very high	Very high	Very high	High	Moderate	Moderate	Low

	UV index (midday)	Level
Jan	2	Low
Feb	3	Moderate
Mar	6	High
Apr	8	Very high
May	9	Very high
Jun	9	Very high
Jul	10	Very high
Aug	8	Very high
Sep	6	High
Oct	4	Moderate
Nov	2	Moderate
Dec	2	Low

Location & terrain

Where is Aosta?

Aosta sits at 45.7°N, 7.3°E, 583 m above sea level, in Italy. The nearest listed city is Chamonix, 40 km away.

Topography around Aosta

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

Within 3 km, the terrain around Aosta has large variations in elevation — a maximum elevation change of 983 m around an average of 764 m above sea level; within 16 km, extreme variations in elevation — a maximum elevation change of 3,150 m; within 80 km, extreme variations in elevation — a maximum elevation change of 4,625 m.

The land around Aosta is covered by trees (48%), grassland (27%) and artificial surfaces (23%) within 3 km, trees (48%) and grassland (35%) within 16 km, and trees (42%) and grassland (32%) within 80 km.

3 km

983 m

trees 48%

16 km

3,150 m

trees 48%

80 km

4,625 m

trees 42%

treesgrasslandcroplandartificial surfacesbare terrainsnow and icewatermoss and lichen

← August Aosta year-round climate October →Best places to visit in September

September weather nearby: Chamonix 40 km · Martigny-Ville 45 km · Zermatt 46 km · Ivrea 53 km · Sitten 55 km · Sallanches 58 km · Ciriè 60 km · Biella 61 km

Italy travel facts

Travel advisory: Level 2; Exercise Increased Caution
Power plugs: Type C / F / L; 230 V · 50 Hz
Prices: ≈ 69% of US; price level, 2025
GDP per capita: $43,309; 2025
Happiness: 6.6 / 10; World Happiness, 2025
Safe drinking water: 97%; of population, 2024
Homicide rate: 0.6; per 100k, 2023
Road deaths: 5.3; per 100k/yr, 2019
Income group: High; World Bank
English: Moderate; EF EPI 513
Religion

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 Aosta (45.7376°, 7.3172°, elevation 583 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).

	Avg high (°C)	Avg low (°C)
1	14	5
2	14	5
3	14	4
4	14	4
5	13	4
6	13	4
7	13	4
8	13	4
9	13	4
10	13	4
11	13	3
12	12	3
13	12	3
14	12	3
15	12	3
16	12	3
17	12	3
18	11	3
19	11	2
20	11	2
21	11	2
22	11	2
23	11	2
24	10	2
25	10	2
26	10	2
27	10	1
28	10	1
29	10	1
30	9	1

	Clearer (%)	Cloudier (%)
1	59	41
2	59	41
3	59	41
4	58	42
5	58	42
6	57	43
7	57	43
8	56	44
9	56	44
10	56	44
11	54	46
12	54	46
13	52	48
14	52	48
15	50	50
16	50	50
17	48	52
18	47	53
19	46	54
20	45	55
21	45	55
22	44	56
23	43	57
24	43	57
25	43	57
26	43	57
27	43	57
28	42	58
29	41	59
30	41	59

	Rain chance (%)	Snow chance (%)
1	42	6
2	42	6
3	43	6
4	43	6
5	43	7
6	43	7
7	43	7
8	42	7
9	42	7
10	42	8
11	42	8
12	42	8
13	42	8
14	42	9
15	42	9
16	42	10
17	42	10
18	42	10
19	42	11
20	42	11
21	42	12
22	42	12
23	42	12
24	42	13
25	43	14
26	43	14
27	43	15
28	43	16
29	44	17
30	44	17

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100

	Avg high (°C)	Avg low (°C)
1	14	5
2	14	5
3	14	4
4	14	4
5	13	4
6	13	4
7	13	4
8	13	4
9	13	4
10	13	4
11	13	3
12	12	3
13	12	3
14	12	3
15	12	3
16	12	3
17	12	3
18	11	3
19	11	2
20	11	2
21	11	2
22	11	2
23	11	2
24	10	2
25	10	2
26	10	2
27	10	1
28	10	1
29	10	1
30	9	1

	Clearer (%)	Cloudier (%)
1	59	41
2	59	41
3	59	41
4	58	42
5	58	42
6	57	43
7	57	43
8	56	44
9	56	44
10	56	44
11	54	46
12	54	46
13	52	48
14	52	48
15	50	50
16	50	50
17	48	52
18	47	53
19	46	54
20	45	55
21	45	55
22	44	56
23	43	57
24	43	57
25	43	57
26	43	57
27	43	57
28	42	58
29	41	59
30	41	59

	Rain chance (%)	Snow chance (%)
1	42	6
2	42	6
3	43	6
4	43	6
5	43	7
6	43	7
7	43	7
8	42	7
9	42	7
10	42	8
11	42	8
12	42	8
13	42	8
14	42	9
15	42	9
16	42	10
17	42	10
18	42	10
19	42	11
20	42	11
21	42	12
22	42	12
23	42	12
24	42	13
25	43	14
26	43	14
27	43	15
28	43	16
29	44	17
30	44	17

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100

	Avg high (°C)	Avg low (°C)
1	14	5
2	14	5
3	14	4
4	14	4
5	13	4
6	13	4
7	13	4
8	13	4
9	13	4
10	13	4
11	13	3
12	12	3
13	12	3
14	12	3
15	12	3
16	12	3
17	12	3
18	11	3
19	11	2
20	11	2
21	11	2
22	11	2
23	11	2
24	10	2
25	10	2
26	10	2
27	10	1
28	10	1
29	10	1
30	9	1

	Clearer (%)	Cloudier (%)
1	59	41
2	59	41
3	59	41
4	58	42
5	58	42
6	57	43
7	57	43
8	56	44
9	56	44
10	56	44
11	54	46
12	54	46
13	52	48
14	52	48
15	50	50
16	50	50
17	48	52
18	47	53
19	46	54
20	45	55
21	45	55
22	44	56
23	43	57
24	43	57
25	43	57
26	43	57
27	43	57
28	42	58
29	41	59
30	41	59

	Rain chance (%)	Snow chance (%)
1	42	6
2	42	6
3	43	6
4	43	6
5	43	7
6	43	7
7	43	7
8	42	7
9	42	7
10	42	8
11	42	8
12	42	8
13	42	8
14	42	9
15	42	9
16	42	10
17	42	10
18	42	10
19	42	11
20	42	11
21	42	12
22	42	12
23	42	12
24	42	13
25	43	14
26	43	14
27	43	15
28	43	16
29	44	17
30	44	17

	Dry (%)
1	100
2	100
3	100
4	100
5	100
6	100
7	100
8	100
9	100
10	100
11	100
12	100
13	100
14	100
15	100
16	100
17	100
18	100
19	100
20	100
21	100
22	100
23	100
24	100
25	100
26	100
27	100
28	100
29	100
30	100