Trondheim weather in September

In September, Trondheim sees average daytime highs of 14°C and overnight lows near 7°C, with 102 mm of precipitation across 14.8 wet days and about 12.7 hours of daylight. It is the 4th-warmest and 1st-wettest month of the year here.

Highs ease over the month, from about 16°C in the first days to 12°C by the end. The sky is clear or mostly clear about 16% of the time in September, and the air most often feels dry.

Daylight stretches from about 14 h 12 min at the start of September to 11 h 06 min by month's end. Set against the rest of the year, September is Trondheim's 3rd-clearest and 7th-windiest month. For the whole year in context, see Trondheim's year-round climate.

Daytime high: 14°; 4th warmest
Overnight low: 7°; 9th coldest
Precipitation: 102 mm; 14.8 wet days
Daylight: 12 h 36 min; 5:54 AM – 6:31 PM
Cloud cover: 72%; 3rd clearest
Wind: 9 km/h; 7th windiest
Solar energy: 2.16 kWh/m²
Travel score: 3.6; out of 10

Trondheim is city in Trøndelag, Norway.

Air quality: Good; PM2.5 5.7 µg/m³ · 2019
Density: 3,766/km²; people per km²
Founded: ~997 CE

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

← August Trondheim 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 16°C in the first days to 12°C by the end.

A typical September day in Trondheim reaches about 14°C in the afternoon and slips back to 7°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 10°C and 19°C. Set against its neighbours, September runs about 4°C cooler than August and about 6°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)	17	16	16	16	16	16	16	16	16	15	15	15	15	15	15	14	14	14	14	14	14	13	13	13	13	13	12	12	12	12
Avg low (°C)	9	9	9	9	9	9	8	8	8	8	8	8	8	8	8	7	7	7	7	7	7	7	6	6	6	6	6	6	6	5

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

How September really feels in Trondheim

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.

Trondheim weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 1st-wettest month here — the current month is highlighted below.

Month	High / Low (°C)	Rainfall (mm)	Wet days	Snow days	Daylight (hours)	Travel score
Jan	0° / -5°	96	15.9	12.7	5.2	0.0
Feb	1° / -5°	84	14.2	11.9	8.1	0.0
Mar	4° / -3°	88	15.4	10.8	11.2	0.1
Apr	9° / 1°	67	13.6	5.4	14.5	1.6
May	13° / 5°	70	15.6	1.4	17.7	3.2
Jun	16° / 8°	95	15.6	0	19.8	4.3
Jul	19° / 11°	85	14.8	0	18.9	5.3
Aug	19° / 11°	99	14.9	0	15.9	5.1
Sep	14° / 7°	102	14.8	0	12.7	3.6
Oct	8° / 3°	87	15.2	2.8	9.4	1.3
Nov	3° / -1°	79	13.2	7.3	6.2	0.0
Dec	1° / -4°	94	15.3	10.7	4.2	0.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 16% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 11% of September, with mostly cloudy or overcast conditions the remaining 73%.

	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 (%)	24	25	25	25	26	27	27	27	27	27	29	29	29	29	29	28	27	28	27	27	27	26	27	27	27	26	26	26	26	27
Cloudier (%)	76	75	75	75	74	73	73	73	73	73	71	71	71	71	71	72	73	72	73	73	73	74	73	73	73	74	74	74	74	73

	Clearer (%)	Cloudier (%)
1	24	76
2	25	75
3	25	75
4	25	75
5	26	74
6	27	73
7	27	73
8	27	73
9	27	73
10	27	73
11	29	71
12	29	71
13	29	71
14	29	71
15	29	71
16	28	72
17	27	73
18	28	72
19	27	73
20	27	73
21	27	73
22	26	74
23	27	73
24	27	73
25	27	73
26	26	74
27	26	74
28	26	74
29	26	74
30	27	73

Chance of precipitation in September

Any precipitationSnow

Trondheim gets around 102 mm of rain and snow over 14.8 wet days in September, the wettest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 50% and peaks near 51% 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 (%)	51	51	51	51	51	51	51	51	51	51	51	51	51	51	51	51	51	51	51	50	50	50	49	49	49	49	49	49	49	48
Snow chance (%)	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	1	1	1	1	2

	Rain chance (%)	Snow chance (%)
1	51	0
2	51	0
3	51	0
4	51	0
5	51	0
6	51	0
7	51	0
8	51	0
9	51	0
10	51	0
11	51	0
12	51	0
13	51	0
14	51	0
15	51	0
16	51	0
17	51	0
18	51	0
19	51	0
20	50	0
21	50	0
22	50	0
23	49	0
24	49	0
25	49	0
26	49	1
27	49	1
28	49	1
29	49	1
30	48	2

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 99% 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 (%)	95	96	96	96	97	97	98	98	98	99	99	99	99	99	99	99	99	99	99	99	99	99	100	100	100	100	100	100	100	100
Comfortable (%)	5	4	4	4	3	3	2	2	2	1	1	1	1	1	1	1	1	1	1	1	1	1	0	0	0	0	0	0	0	0

	Dry (%)	Comfortable (%)
1	95	5
2	96	4
3	96	4
4	96	4
5	97	3
6	97	3
7	98	2
8	98	2
9	98	2
10	99	1
11	99	1
12	99	1
13	99	1
14	99	1
15	99	1
16	99	1
17	99	1
18	99	1
19	99	1
20	99	1
21	99	1
22	99	1
23	100	0
24	100	0
25	100	0
26	100	0
27	100	0
28	100	0
29	100	0
30	100	0

Wind in September

Winds average 9 km/h in September.

Across September, daily wind ranges from about 8 km/h on the calmest days to 9 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)	8	8	8	8	8	8	9	9	9	9	9	9	9	9	9	9	9	9	9	9	9	9	9	9	9	9	9	9	9	9
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	8	calm
2	8	calm
3	8	calm
4	8	calm
5	8	calm
6	8	calm
7	9	calm
8	9	calm
9	9	calm
10	9	calm
11	9	calm
12	9	calm
13	9	calm
14	9	calm
15	9	calm
16	9	calm
17	9	calm
18	9	calm
19	9	calm
20	9	calm
21	9	calm
22	9	calm
23	9	calm
24	9	calm
25	9	calm
26	9	calm
27	9	calm
28	9	calm
29	9	calm
30	9	calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 14 h 12 min at the start of September to 11 h 06 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 186 minutes over September. Sunrise moves from 5:11 AM to 6:34 AM, and sunset from 7:25 PM to 5:41 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)	14.2	14.1	14.0	13.9	13.8	13.7	13.6	13.5	13.4	13.3	13.2	13.0	12.9	12.8	12.7	12.6	12.5	12.4	12.3	12.2	12.1	12.0	11.9	11.8	11.7	11.5	11.4	11.3	11.2	11.1
Sunrise (AM)	5:11	5:14	5:17	5:20	5:23	5:26	5:28	5:31	5:34	5:37	5:40	5:43	5:46	5:48	5:51	5:54	5:57	6:00	6:03	6:06	6:08	6:11	6:14	6:17	6:20	6:23	6:26	6:29	6:31	6:34
Sunset (PM)	7:25	7:22	7:18	7:14	7:11	7:07	7:04	7:00	6:56	6:53	6:49	6:46	6:42	6:38	6:35	6:31	6:28	6:24	6:21	6:17	6:13	6:10	6:06	6:03	5:59	5:55	5:52	5:48	5:45	5:41

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	14.2	5:11	7:25
2	14.1	5:14	7:22
3	14.0	5:17	7:18
4	13.9	5:20	7:14
5	13.8	5:23	7:11
6	13.7	5:26	7:07
7	13.6	5:28	7:04
8	13.5	5:31	7:00
9	13.4	5:34	6:56
10	13.3	5:37	6:53
11	13.2	5:40	6:49
12	13.0	5:43	6:46
13	12.9	5:46	6:42
14	12.8	5:48	6:38
15	12.7	5:51	6:35
16	12.6	5:54	6:31
17	12.5	5:57	6:28
18	12.4	6:00	6:24
19	12.3	6:03	6:21
20	12.2	6:06	6:17
21	12.1	6:08	6:13
22	12.0	6:11	6:10
23	11.9	6:14	6:06
24	11.8	6:17	6:03
25	11.7	6:20	5:59
26	11.5	6:23	5:55
27	11.4	6:26	5:52
28	11.3	6:29	5:48
29	11.2	6:31	5:45
30	11.1	6:34	5:41

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 2.16 kWh/m².

For context, solar energy here swings from a low near 0.06 kWh/m² to a high of 4.7 kWh/m² in June across the year — September's 2.16 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)	2.8	2.7	2.7	2.6	2.6	2.6	2.5	2.5	2.4	2.4	2.4	2.3	2.3	2.2	2.2	2.1	2.1	2.0	2.0	1.9	1.9	1.9	1.8	1.8	1.7	1.7	1.7	1.6	1.6	1.6
Level	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim	Dim

	Solar energy (kWh/m²)	Level
1	2.8	Moderate
2	2.7	Moderate
3	2.7	Moderate
4	2.6	Moderate
5	2.6	Moderate
6	2.6	Moderate
7	2.5	Moderate
8	2.5	Moderate
9	2.4	Moderate
10	2.4	Moderate
11	2.4	Moderate
12	2.3	Moderate
13	2.3	Moderate
14	2.2	Moderate
15	2.2	Moderate
16	2.1	Moderate
17	2.1	Moderate
18	2.0	Moderate
19	2.0	Dim
20	1.9	Dim
21	1.9	Dim
22	1.9	Dim
23	1.8	Dim
24	1.8	Dim
25	1.7	Dim
26	1.7	Dim
27	1.7	Dim
28	1.6	Dim
29	1.6	Dim
30	1.6	Dim

Planning a trip in September

Is September a good time to visit Trondheim?

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

3.6

Sightseeing

4th-best month of the year

0.2

Beach & pool

4th-best month of the year

September is a weaker month for outdoor sightseeing in Trondheim.

What to pack for Trondheim in September

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

In September, Trondheim sees daytime highs around 14°C and nights near 7°C. Pack rain gear. Worth having: a warm layer. About 15 days see rain.

rain geara warm layer

Sea temperature near Trondheim in September

The nearest coast averages about 13°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 55 km away) is warmest in August at about 14°C and coldest in March near 5°C.

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

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Sea temperature (°C)	6	6	5	6	8	10	13	14	13	11	9	7
Comfort	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing

	Sea temperature (°C)	Comfort
Jan	6	Bracing
Feb	6	Bracing
Mar	5	Bracing
Apr	6	Bracing
May	8	Bracing
Jun	10	Bracing
Jul	13	Bracing
Aug	14	Bracing
Sep	13	Bracing
Oct	11	Bracing
Nov	9	Bracing
Dec	7	Bracing

UV index in Trondheim in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 2. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Trondheim peaks around July 13 at about 4 (moderate) — a little sun protection helps at midday. It bottoms out near January 1 at about 0 (low).

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

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
UV index (midday)	0	0	1	2	4	4	5	4	2	1	0	0
Level	Low	Low	Low	Moderate	Moderate	Moderate	Moderate	Moderate	Low	Low	Low	Low

	UV index (midday)	Level
Jan	0	Low
Feb	0	Low
Mar	1	Low
Apr	2	Moderate
May	4	Moderate
Jun	4	Moderate
Jul	5	Moderate
Aug	4	Moderate
Sep	2	Low
Oct	1	Low
Nov	0	Low
Dec	0	Low

Location & terrain

Where is Trondheim?

Trondheim sits at 63.4°N, 10.4°E, 18 m above sea level, in Norway. The nearest listed city is Stjørdalshalsen, 27 km away.

Topography around Trondheim

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

Within 3 km, the terrain around Trondheim has significant variations in elevation — a maximum elevation change of 312 m around an average of 52 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 558 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,431 m.

The land around Trondheim is covered by trees (33%), artificial surfaces (31%) and water (31%) within 3 km, water (48%) and trees (34%) within 16 km, and grassland (37%), trees (36%) and water (22%) within 80 km.

3 km

312 m

trees 33%

16 km

558 m

water 48%

80 km

1,431 m

grassland 37%

treesgrasslandcroplandartificial surfaceswatermoss and lichen

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

September weather nearby: Stjørdalshalsen 27 km · Levanger 57 km · Åre 134 km · Kristiansund 138 km · Molde 180 km · Östersund 214 km · Alesund 239 km · Lillehammer 257 km

Norway travel facts

Travel advisory: Level 1; Exercise Normal Precautions
Power plugs: Type C / F; 230 V · 50 Hz
Prices: ≈ 91% of US; price level, 2025
GDP per capita: $94,594; 2025
Happiness: 7.2 / 10; World Happiness, 2025
Safe drinking water: 99%; of population, 2024
Homicide rate: 0.7; per 100k, 2023
Road deaths: 2.1; per 100k/yr, 2019
Income group: High; World Bank
English: Very high; EF EPI 613
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 Trondheim (63.4305°, 10.3951°, elevation 18 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).

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

	Clearer (%)	Cloudier (%)
1	24	76
2	25	75
3	25	75
4	25	75
5	26	74
6	27	73
7	27	73
8	27	73
9	27	73
10	27	73
11	29	71
12	29	71
13	29	71
14	29	71
15	29	71
16	28	72
17	27	73
18	28	72
19	27	73
20	27	73
21	27	73
22	26	74
23	27	73
24	27	73
25	27	73
26	26	74
27	26	74
28	26	74
29	26	74
30	27	73

	Rain chance (%)	Snow chance (%)
1	51	0
2	51	0
3	51	0
4	51	0
5	51	0
6	51	0
7	51	0
8	51	0
9	51	0
10	51	0
11	51	0
12	51	0
13	51	0
14	51	0
15	51	0
16	51	0
17	51	0
18	51	0
19	51	0
20	50	0
21	50	0
22	50	0
23	49	0
24	49	0
25	49	0
26	49	1
27	49	1
28	49	1
29	49	1
30	48	2

	Dry (%)	Comfortable (%)
1	95	5
2	96	4
3	96	4
4	96	4
5	97	3
6	97	3
7	98	2
8	98	2
9	98	2
10	99	1
11	99	1
12	99	1
13	99	1
14	99	1
15	99	1
16	99	1
17	99	1
18	99	1
19	99	1
20	99	1
21	99	1
22	99	1
23	100	0
24	100	0
25	100	0
26	100	0
27	100	0
28	100	0
29	100	0
30	100	0

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

	Clearer (%)	Cloudier (%)
1	24	76
2	25	75
3	25	75
4	25	75
5	26	74
6	27	73
7	27	73
8	27	73
9	27	73
10	27	73
11	29	71
12	29	71
13	29	71
14	29	71
15	29	71
16	28	72
17	27	73
18	28	72
19	27	73
20	27	73
21	27	73
22	26	74
23	27	73
24	27	73
25	27	73
26	26	74
27	26	74
28	26	74
29	26	74
30	27	73

	Rain chance (%)	Snow chance (%)
1	51	0
2	51	0
3	51	0
4	51	0
5	51	0
6	51	0
7	51	0
8	51	0
9	51	0
10	51	0
11	51	0
12	51	0
13	51	0
14	51	0
15	51	0
16	51	0
17	51	0
18	51	0
19	51	0
20	50	0
21	50	0
22	50	0
23	49	0
24	49	0
25	49	0
26	49	1
27	49	1
28	49	1
29	49	1
30	48	2

	Dry (%)	Comfortable (%)
1	95	5
2	96	4
3	96	4
4	96	4
5	97	3
6	97	3
7	98	2
8	98	2
9	98	2
10	99	1
11	99	1
12	99	1
13	99	1
14	99	1
15	99	1
16	99	1
17	99	1
18	99	1
19	99	1
20	99	1
21	99	1
22	99	1
23	100	0
24	100	0
25	100	0
26	100	0
27	100	0
28	100	0
29	100	0
30	100	0

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

	Clearer (%)	Cloudier (%)
1	24	76
2	25	75
3	25	75
4	25	75
5	26	74
6	27	73
7	27	73
8	27	73
9	27	73
10	27	73
11	29	71
12	29	71
13	29	71
14	29	71
15	29	71
16	28	72
17	27	73
18	28	72
19	27	73
20	27	73
21	27	73
22	26	74
23	27	73
24	27	73
25	27	73
26	26	74
27	26	74
28	26	74
29	26	74
30	27	73

	Rain chance (%)	Snow chance (%)
1	51	0
2	51	0
3	51	0
4	51	0
5	51	0
6	51	0
7	51	0
8	51	0
9	51	0
10	51	0
11	51	0
12	51	0
13	51	0
14	51	0
15	51	0
16	51	0
17	51	0
18	51	0
19	51	0
20	50	0
21	50	0
22	50	0
23	49	0
24	49	0
25	49	0
26	49	1
27	49	1
28	49	1
29	49	1
30	48	2

	Dry (%)	Comfortable (%)
1	95	5
2	96	4
3	96	4
4	96	4
5	97	3
6	97	3
7	98	2
8	98	2
9	98	2
10	99	1
11	99	1
12	99	1
13	99	1
14	99	1
15	99	1
16	99	1
17	99	1
18	99	1
19	99	1
20	99	1
21	99	1
22	99	1
23	100	0
24	100	0
25	100	0
26	100	0
27	100	0
28	100	0
29	100	0
30	100	0