Herisau weather in September

In September, Herisau sees average daytime highs of 18°C and overnight lows near 11°C, with 127 mm of rain across 13.7 wet days and about 12.4 hours of daylight. It is the 4th-warmest and 5th-wettest month of the year here.

Highs ease over the month, from about 20°C in the first days to 16°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 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 Herisau's 4th-clearest and 9th-windiest month. For the whole year in context, see Herisau's year-round climate.

Daytime high: 18°; 4th warmest
Overnight low: 11°; 9th coldest
Rainfall: 127 mm; 13.7 wet days
Daylight: 12 h 18 min; 6:07 AM – 6:27 PM
Cloud cover: 61%; 4th clearest
Wind: 6 km/h; 9th windiest
Solar energy: 3.54 kWh/m²
Travel score: 5.2; out of 10

← August Herisau 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 20°C in the first days to 16°C by the end.

A typical September day in Herisau reaches about 18°C in the afternoon and slips back to 11°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 13°C and 23°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)	20	20	20	20	19	19	19	19	19	19	19	18	18	18	18	18	18	18	17	17	17	17	17	17	17	16	16	16	16	16
Avg low (°C)	13	13	13	13	12	12	12	12	12	12	12	12	12	11	11	11	11	11	11	11	11	10	10	10	10	10	10	10	10	10

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

How September really feels in Herisau

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.

Herisau weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 5th-wettest month here — the current month is highlighted below.

Month	High / Low (°C)	Rainfall (mm)	Wet days	Snow days	Daylight (hours)	Travel score
Jan	3° / -2°	88	12.7	8.4	8.7	0.0
Feb	4° / -2°	80	11.7	8.3	9.9	0.1
Mar	9° / 2°	100	14.8	6.6	11.6	1.6
Apr	13° / 5°	103	14.5	3.3	13.3	3.2
May	17° / 10°	155	17.2	0.3	14.9	4.6
Jun	21° / 13°	172	17.4	0	15.7	5.3
Jul	23° / 15°	174	17.5	0	15.3	5.7
Aug	22° / 15°	175	16.8	0	14.1	5.8
Sep	18° / 11°	127	13.7	0	12.4	5.2
Oct	13° / 7°	103	12.9	0.9	10.6	3.4
Nov	7° / 3°	103	12.7	4.8	9.1	1.0
Dec	4° / -1°	105	14.1	8.6	8.3	0.0

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 16% of September, with mostly cloudy or overcast conditions the remaining 57%. 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 (%)	48	48	47	47	47	46	46	45	45	44	44	44	43	44	44	42	42	42	42	42	41	42	42	41	41	40	40	38	38	37
Cloudier (%)	52	52	53	53	53	54	54	55	55	56	56	56	57	56	56	58	58	58	58	58	59	58	58	59	59	60	60	62	62	63

	Clearer (%)	Cloudier (%)
1	48	52
2	48	52
3	47	53
4	47	53
5	47	53
6	46	54
7	46	54
8	45	55
9	45	55
10	44	56
11	44	56
12	44	56
13	43	57
14	44	56
15	44	56
16	42	58
17	42	58
18	42	58
19	42	58
20	42	58
21	41	59
22	42	58
23	42	58
24	41	59
25	41	59
26	40	60
27	40	60
28	38	62
29	38	62
30	37	63

Chance of precipitation in September

Any precipitation

Herisau gets around 127 mm of rain over 13.7 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 47% and peaks near 50% on the wettest days.

	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 (%)	50	50	49	49	49	48	48	48	48	48	47	47	47	46	46	46	45	45	45	45	44	44	44	44	44	45	45	46	46	47

	Rain chance (%)
1	50
2	50
3	49
4	49
5	49
6	48
7	48
8	48
9	48
10	48
11	47
12	47
13	47
14	46
15	46
16	46
17	45
18	45
19	45
20	45
21	44
22	44
23	44
24	44
25	44
26	45
27	45
28	46
29	46
30	47

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 71% 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 (%)	54	55	57	59	60	61	62	62	63	64	66	66	67	67	69	70	71	73	74	75	77	78	80	82	83	84	86	87	88	89
Comfortable (%)	31	31	31	30	30	30	30	31	31	31	30	30	30	30	29	28	27	26	25	24	22	21	20	18	17	16	14	13	12	11
Humid (%)	15	14	12	11	10	9	8	7	6	5	4	4	3	3	2	2	2	1	1	1	1	1	0	0	0	0	0	0	0	0

	Dry (%)	Comfortable (%)	Humid (%)
1	54	31	15
2	55	31	14
3	57	31	12
4	59	30	11
5	60	30	10
6	61	30	9
7	62	30	8
8	62	31	7
9	63	31	6
10	64	31	5
11	66	30	4
12	66	30	4
13	67	30	3
14	67	30	3
15	69	29	2
16	70	28	2
17	71	27	2
18	73	26	1
19	74	25	1
20	75	24	1
21	77	22	1
22	78	21	1
23	80	20	0
24	82	18	0
25	83	17	0
26	84	16	0
27	86	14	0
28	87	13	0
29	88	12	0
30	89	11	0

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.

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

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 5:47 AM to 6:27 AM, and sunset from 6:59 PM to 5:58 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)	13.2	13.1	13.1	13.0	13.0	12.9	12.9	12.8	12.7	12.7	12.6	12.6	12.5	12.5	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	11.6	11.6	11.5
Sunrise (AM)	5:47	5:48	5:49	5:51	5:52	5:53	5:55	5:56	5:58	5:59	6:00	6:02	6:03	6:04	6:06	6:07	6:09	6:10	6:11	6:13	6:14	6:15	6:17	6:18	6:20	6:21	6:22	6:24	6:25	6:27
Sunset (PM)	6:59	6:57	6:55	6:52	6:50	6:48	6:46	6:44	6:42	6:40	6:38	6:36	6:34	6:32	6:29	6:27	6:25	6:23	6:21	6:19	6:17	6:15	6:12	6:10	6:08	6:06	6:04	6:02	6:00	5:58

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	13.2	5:47	6:59
2	13.1	5:48	6:57
3	13.1	5:49	6:55
4	13.0	5:51	6:52
5	13.0	5:52	6:50
6	12.9	5:53	6:48
7	12.9	5:55	6:46
8	12.8	5:56	6:44
9	12.7	5:58	6:42
10	12.7	5:59	6:40
11	12.6	6:00	6:38
12	12.6	6:02	6:36
13	12.5	6:03	6:34
14	12.5	6:04	6:32
15	12.4	6:06	6:29
16	12.3	6:07	6:27
17	12.3	6:09	6:25
18	12.2	6:10	6:23
19	12.2	6:11	6:21
20	12.1	6:13	6:19
21	12.0	6:14	6:17
22	12.0	6:15	6:15
23	11.9	6:17	6:12
24	11.9	6:18	6:10
25	11.8	6:20	6:08
26	11.8	6:21	6:06
27	11.7	6:22	6:04
28	11.6	6:24	6:02
29	11.6	6:25	6:00
30	11.5	6:27	5:58

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.54 kWh/m².

For context, solar energy here swings from a low near 1.04 kWh/m² to a high of 5.52 kWh/m² in June across the year — September's 3.54 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)	4.1	4.1	4.1	4.0	4.0	3.9	3.9	3.9	3.8	3.8	3.7	3.7	3.7	3.6	3.6	3.5	3.5	3.4	3.4	3.4	3.3	3.3	3.2	3.2	3.1	3.1	3.0	3.0	2.9	2.9
Level	Bright	Bright	Bright	Bright	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate

	Solar energy (kWh/m²)	Level
1	4.1	Bright
2	4.1	Bright
3	4.1	Bright
4	4.0	Bright
5	4.0	Moderate
6	3.9	Moderate
7	3.9	Moderate
8	3.9	Moderate
9	3.8	Moderate
10	3.8	Moderate
11	3.7	Moderate
12	3.7	Moderate
13	3.7	Moderate
14	3.6	Moderate
15	3.6	Moderate
16	3.5	Moderate
17	3.5	Moderate
18	3.4	Moderate
19	3.4	Moderate
20	3.4	Moderate
21	3.3	Moderate
22	3.3	Moderate
23	3.2	Moderate
24	3.2	Moderate
25	3.1	Moderate
26	3.1	Moderate
27	3.0	Moderate
28	3.0	Moderate
29	2.9	Moderate
30	2.9	Moderate

Planning a trip in September

Is September a good time to visit Herisau?

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

5.2

Sightseeing

4th-best month of the year

1.7

Beach & pool

4th-best month of the year

September is a reasonable time to visit Herisau for sightseeing.

What to pack for Herisau in September

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

In September, Herisau sees daytime highs around 18°C and nights near 11°C. Pack rain gear. About 14 days see rain.

rain gear

UV index in Herisau 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 Herisau peaks around July 16 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 10 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
UV index (midday)	1	2	4	5	7	7	8	7	4	3	2	1
Level	Low	Moderate	Moderate	High	Very high	Very high	Very high	High	Moderate	Moderate	Low	Low

	UV index (midday)	Level
Jan	1	Low
Feb	2	Moderate
Mar	4	Moderate
Apr	5	High
May	7	Very high
Jun	7	Very high
Jul	8	Very high
Aug	7	High
Sep	4	Moderate
Oct	3	Moderate
Nov	2	Low
Dec	1	Low

Location & terrain

Where is Herisau?

Herisau sits at 47.4°N, 9.3°E, 780 m above sea level, in Switzerland. The nearest listed city is Gossau, 4.0 km away.

Topography around Herisau

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

Within 3 km, the terrain around Herisau has significant variations in elevation — a maximum elevation change of 363 m around an average of 781 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 2,025 m; within 80 km, extreme variations in elevation — a maximum elevation change of 3,252 m.

The land around Herisau is covered by grassland (51%) and trees (35%) within 3 km, grassland (53%) and trees (40%) within 16 km, and trees (42%) and grassland (37%) within 80 km.

3 km

363 m

grassland 51%

16 km

2,025 m

grassland 53%

80 km

3,252 m

trees 42%

treesgrasslandcroplandartificial surfacesbare terrainsnow and icewatermoss and lichen

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

September weather nearby: Gossau 4.0 km · Saint Gallen 8.0 km · Wil 19 km · Lustenau 29 km · Feldkirch 29 km · Kreuzlingen 30 km · Hohenems 31 km · Konstanz 31 km

Switzerland travel facts

Travel advisory: Level 1; Exercise Normal Precautions
Power plugs: Type C / J; 230 V · 50 Hz
Prices: ≈ 112% of US; price level, 2025
GDP per capita: $114,769; 2025
Happiness: 7.0 / 10; World Happiness, 2025
Safe drinking water: 97%; of population, 2024
Homicide rate: 0.6; per 100k, 2023
Road deaths: 2.2; per 100k/yr, 2019
Income group: High; World Bank
English: High; EF EPI 564
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 Herisau (47.3862°, 9.2792°, elevation 780 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	20	13
2	20	13
3	20	13
4	20	13
5	19	12
6	19	12
7	19	12
8	19	12
9	19	12
10	19	12
11	19	12
12	18	12
13	18	12
14	18	11
15	18	11
16	18	11
17	18	11
18	18	11
19	17	11
20	17	11
21	17	11
22	17	10
23	17	10
24	17	10
25	17	10
26	16	10
27	16	10
28	16	10
29	16	10
30	16	10

	Clearer (%)	Cloudier (%)
1	48	52
2	48	52
3	47	53
4	47	53
5	47	53
6	46	54
7	46	54
8	45	55
9	45	55
10	44	56
11	44	56
12	44	56
13	43	57
14	44	56
15	44	56
16	42	58
17	42	58
18	42	58
19	42	58
20	42	58
21	41	59
22	42	58
23	42	58
24	41	59
25	41	59
26	40	60
27	40	60
28	38	62
29	38	62
30	37	63

	Rain chance (%)
1	50
2	50
3	49
4	49
5	49
6	48
7	48
8	48
9	48
10	48
11	47
12	47
13	47
14	46
15	46
16	46
17	45
18	45
19	45
20	45
21	44
22	44
23	44
24	44
25	44
26	45
27	45
28	46
29	46
30	47

	Dry (%)	Comfortable (%)	Humid (%)
1	54	31	15
2	55	31	14
3	57	31	12
4	59	30	11
5	60	30	10
6	61	30	9
7	62	30	8
8	62	31	7
9	63	31	6
10	64	31	5
11	66	30	4
12	66	30	4
13	67	30	3
14	67	30	3
15	69	29	2
16	70	28	2
17	71	27	2
18	73	26	1
19	74	25	1
20	75	24	1
21	77	22	1
22	78	21	1
23	80	20	0
24	82	18	0
25	83	17	0
26	84	16	0
27	86	14	0
28	87	13	0
29	88	12	0
30	89	11	0

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

	Clearer (%)	Cloudier (%)
1	48	52
2	48	52
3	47	53
4	47	53
5	47	53
6	46	54
7	46	54
8	45	55
9	45	55
10	44	56
11	44	56
12	44	56
13	43	57
14	44	56
15	44	56
16	42	58
17	42	58
18	42	58
19	42	58
20	42	58
21	41	59
22	42	58
23	42	58
24	41	59
25	41	59
26	40	60
27	40	60
28	38	62
29	38	62
30	37	63

	Rain chance (%)
1	50
2	50
3	49
4	49
5	49
6	48
7	48
8	48
9	48
10	48
11	47
12	47
13	47
14	46
15	46
16	46
17	45
18	45
19	45
20	45
21	44
22	44
23	44
24	44
25	44
26	45
27	45
28	46
29	46
30	47

	Dry (%)	Comfortable (%)	Humid (%)
1	54	31	15
2	55	31	14
3	57	31	12
4	59	30	11
5	60	30	10
6	61	30	9
7	62	30	8
8	62	31	7
9	63	31	6
10	64	31	5
11	66	30	4
12	66	30	4
13	67	30	3
14	67	30	3
15	69	29	2
16	70	28	2
17	71	27	2
18	73	26	1
19	74	25	1
20	75	24	1
21	77	22	1
22	78	21	1
23	80	20	0
24	82	18	0
25	83	17	0
26	84	16	0
27	86	14	0
28	87	13	0
29	88	12	0
30	89	11	0

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

	Clearer (%)	Cloudier (%)
1	48	52
2	48	52
3	47	53
4	47	53
5	47	53
6	46	54
7	46	54
8	45	55
9	45	55
10	44	56
11	44	56
12	44	56
13	43	57
14	44	56
15	44	56
16	42	58
17	42	58
18	42	58
19	42	58
20	42	58
21	41	59
22	42	58
23	42	58
24	41	59
25	41	59
26	40	60
27	40	60
28	38	62
29	38	62
30	37	63

	Rain chance (%)
1	50
2	50
3	49
4	49
5	49
6	48
7	48
8	48
9	48
10	48
11	47
12	47
13	47
14	46
15	46
16	46
17	45
18	45
19	45
20	45
21	44
22	44
23	44
24	44
25	44
26	45
27	45
28	46
29	46
30	47

	Dry (%)	Comfortable (%)	Humid (%)
1	54	31	15
2	55	31	14
3	57	31	12
4	59	30	11
5	60	30	10
6	61	30	9
7	62	30	8
8	62	31	7
9	63	31	6
10	64	31	5
11	66	30	4
12	66	30	4
13	67	30	3
14	67	30	3
15	69	29	2
16	70	28	2
17	71	27	2
18	73	26	1
19	74	25	1
20	75	24	1
21	77	22	1
22	78	21	1
23	80	20	0
24	82	18	0
25	83	17	0
26	84	16	0
27	86	14	0
28	87	13	0
29	88	12	0
30	89	11	0