Trollhättan weather in September

In September, Trollhättan sees average daytime highs of 16°C and overnight lows near 9°C, with 75 mm of rain across 11.6 wet days and about 12.5 hours of daylight. It is the 4th-warmest and 5th-wettest month of the year here.

Highs ease over the month, from about 18°C in the first days to 14°C by the end. The sky is clear or mostly clear about 22% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 48 min at the start of September to 11 h 18 min by month's end. Set against the rest of the year, September is Trollhättan's 6th-clearest and 7th-windiest month. For the whole year in context, see Trollhättan's year-round climate.

Daytime high
16°
4th warmest
Overnight low
9th coldest
Rainfall
75 mm
11.6 wet days
Daylight
12 h 30 min
5:50 AM – 6:20 PM
Cloud cover
65%
6th clearest
Wind
13 km/h
7th windiest
Solar energy
2.7 kWh/m²
Travel score
4.7
out of 10

Trollhättan is urban area in Trollhättan Municipality, Sweden.

Founded
1916

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 18°C in the first days to 14°C by the end.

A typical September day in Trollhättan reaches about 16°C in the afternoon and slips back to 9°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 19°C. Set against its neighbours, September runs about 4°C cooler than August and about 5°C warmer than October.

10°15°20°25°151015202530
Avg high (°C)Avg low (°C)
11811
21810
31810
41810
51810
61710
71710
81710
91710
101710
11179
12179
13169
14169
15169
16169
17169
18169
19159
20158
21158
22158
23158
24158
25148
26148
27148
28147
29147
30147

How September really feels in Trollhättan

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.

Trollhättan 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.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan / -3°6011.25.76.80.0
Feb / -3°469.35.68.90.0
Mar / -1°438.93.911.40.4
Apr11° / 499.41.1142.6
May15° / 6211.30.116.44.6
Jun19° / 10°8613.1017.85.5
Jul21° / 13°8412.4017.26.1
Aug20° / 12°9013.7015.15.8
Sep16° / 7511.6012.54.7
Oct11° / 7712.80.59.92.3
Nov / 61122.37.50.4
Dec / -1°6511.84.76.20.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 22% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 17% of September, with mostly cloudy or overcast conditions the remaining 61%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
13961
24060
34060
43961
54060
64060
74060
84060
94060
104159
114060
124060
134060
144060
153961
163961
173961
183961
193961
203862
213862
223862
233763
243763
253763
263763
273763
283763
293664
303664

Chance of precipitation in September

Any precipitation

Trollhättan gets around 75 mm of rain over 11.6 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 40% and peaks near 45% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%151015202530
Rain chance (%)
145
244
343
443
542
642
742
842
942
1042
1141
1241
1341
1440
1540
1639
1739
1838
1938
2038
2137
2237
2336
2436
2536
2636
2736
2837
2937
3038

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 89% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
177203
278193
380182
481172
582162
683161
784151
885141
985141
1086131
1187121
1288120
1389110
1490100
159190
169190
179280
189370
199370
209460
219460
229460
239550
249550
259550
269640
279640
289640
299640
309730

Wind in September

Winds average 13 km/h in September.

Across September, daily wind ranges from about 12 km/h on the calmest days to 14 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202530
Wind speed (km/h)Feels
112light breeze
212light breeze
312light breeze
412light breeze
513light breeze
613light breeze
713light breeze
813light breeze
913light breeze
1013light breeze
1113light breeze
1213light breeze
1313light breeze
1413light breeze
1513light breeze
1613light breeze
1713light breeze
1813light breeze
1913light breeze
2013light breeze
2113light breeze
2213light breeze
2313light breeze
2413light breeze
2513light breeze
2613light breeze
2713light breeze
2814light breeze
2914light breeze
3014light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 48 min at the start of September to 11 h 18 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 150 minutes over September. Sunrise moves from 5:17 AM to 6:22 AM, and sunset from 7:04 PM to 5:39 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.85:177:04
213.75:197:02
313.65:216:59
413.55:236:56
513.55:266:53
613.45:286:50
713.35:306:47
813.25:326:44
913.15:356:41
1013.05:376:38
1112.95:396:35
1212.85:416:32
1312.85:436:29
1412.75:466:26
1512.65:486:23
1612.55:506:20
1712.45:526:17
1812.35:556:14
1912.25:576:11
2012.25:596:08
2112.16:016:05
2212.06:046:02
2311.96:065:59
2411.86:085:56
2511.76:105:53
2611.66:135:50
2711.56:155:47
2811.56:175:45
2911.46:195:42
3011.36:225:39

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 2.7 kWh/m².

For context, solar energy here swings from a low near 0.25 kWh/m² to a high of 5.72 kWh/m² in June across the year — September's 2.7 kWh/m² falls in the middle.

01234151015202530
Solar energy (kWh/m²)Level
13.4Moderate
23.3Moderate
33.3Moderate
43.3Moderate
53.2Moderate
63.1Moderate
73.1Moderate
83.0Moderate
93.0Moderate
103.0Moderate
112.9Moderate
122.9Moderate
132.8Moderate
142.7Moderate
152.7Moderate
162.6Moderate
172.6Moderate
182.5Moderate
192.5Moderate
202.5Moderate
212.4Moderate
222.4Moderate
232.3Moderate
242.3Moderate
252.2Moderate
262.2Moderate
272.1Moderate
282.1Moderate
292.0Moderate
302.0Dim
Planning a trip in September

Is September a good time to visit Trollhättan?

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

4.7
Sightseeing
4th-best month of the year
0.7
Beach & pool
4th-best month of the year

September is a reasonable time to visit Trollhättan for sightseeing.

What to pack for Trollhättan in September

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

In September, Trollhättan sees daytime highs around 16°C and nights near 9°C. Worth packing: a warm layer and rain gear. About 12 days see rain.

a warm layerrain gear

Sea temperature near Trollhättan in September

The nearest coast averages about 15°C in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 56 km away) is warmest in August at about 18°C and coldest in February near 3°C.

The water stays below 20°C all year — cool enough that most swimmers want a wetsuit.

0°5°10°15°20°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshing
Sea temperature (°C)Comfort
Jan4Bracing
Feb3Bracing
Mar3Bracing
Apr6Bracing
May11Bracing
Jun15Bracing
Jul17Cool
Aug18Cool
Sep15Cool
Oct12Bracing
Nov9Bracing
Dec6Bracing

UV index in Trollhättan in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 3. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Trollhättan peaks around June 17 at about 5 (moderate) — a little sun protection helps at midday. It bottoms out near December 20 at about 0 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 4 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateLowJun 17UV 5Dec 20UV 0
UV index (midday)Level
Jan0Low
Feb1Low
Mar2Low
Apr3Moderate
May5Moderate
Jun5Moderate
Jul5Moderate
Aug4Moderate
Sep3Moderate
Oct1Low
Nov1Low
Dec0Low
Location & terrain

Where is Trollhättan?

Trollhättan sits at 58.3°N, 12.3°E, 49 m above sea level, in Sweden. The nearest listed city is Vänersborg, 11 km away.

Topography around Trollhättan

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

Within 3 km, the terrain around Trollhättan has only modest variations in elevation — a maximum elevation change of 107 m around an average of 57 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 186 m; within 80 km, significant variations in elevation — a maximum elevation change of 343 m.

The land around Trollhättan is covered by trees (50%) and artificial surfaces (24%) within 3 km, trees (63%) within 16 km, and trees (50%) and water (28%) within 80 km.

3 km
107 m
16 km
186 m
80 km
343 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Vänersborg 11 km · Uddevalla 21 km · Alingsås 42 km · Kungälv 49 km · Lidköping 56 km · Lerum 57 km · Partille 61 km · Björlanda 63 km

Sweden travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type C / F
230 V · 50 Hz
Prices
≈ 87% of US
price level, 2025
GDP per capita
$63,133
2025
Happiness
7.3 / 10
World Happiness, 2025
Safe drinking water
100%
of population, 2024
Homicide rate
1.1
per 100k, 2023
Road deaths
3.1
per 100k/yr, 2019
Income group
High
World Bank
English
Very high
EF EPI 609
Religion
Church of Sweden 54%none or unspecified 37%other 9%

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 Trollhättan (58.2837°, 12.2886°, elevation 49 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. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. 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).