SeasonMapTrondheim weather in September
Norway
September in Trondheim: cool, rainy, with clean air — a great time to visit.
#5 of 12 months in Trondheim · #942 of 1383 destinations to visit in September · comfort 71/100 (tier B)
Updated September 2026 · climate normals from ERA5 reanalysis
Traveller notes on Trondheim in September
Other months in Trondheim
June in Trondheim barely gets dark — over twenty hours of daylight — and the forum's own saying is that if you are not happy with the weather, give it five minutes. Expect 10 to 20°C, some nights down to 5, occasional days above 25, and the honest possibility of cold, windy and rainy instead. They call June relatively dry, though the record still shows rain on about thirteen days. The packing list is a list precisely because you may need all of it: windproof and waterproof shell, a woollen sweater, long trousers, hiking shoes, and shorts. June versus July is not worth agonising over — the difference is statistical.
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Trondheim climate normals — September
| Daytime high | 14°C / 58°F | 🙂 cool |
|---|---|---|
| Nighttime low | 8°C / 46°F | |
| Sea temperature | 13°C / 55°F | 🥶 cold sea |
| Rainfall | 121 mm / 4.8 in | 🌧 rainy |
| Rainy days | 18 days | |
| Humidity | 86% | 💦 very humid |
| Dew point | 9°C / 48°F | |
| Sunshine | 6.7 h/day | |
| Daylight | 13 h | |
| Wind | 13 km/h / 8 mph | |
| Snowfall | 0.1 cm / 0 in | |
| Air quality (US AQI) | 27 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Crowds in Trondheim in September
How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.
BusyAutumn break in Norway, school holidays in 3 of the markets that fill it(estimated)
Peak crowdsBusyShoulder seasonQuiet
Best months for Trondheim's weather
Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).
Fair weatherTrondheim's weather peaks June–August.
Best weatherFair weatherToughest weather
What's on in Trondheim in September
Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.
- Season
Pilgrim walking season
1 Jun – 15 Sep · usuallyTrail seasonThe St Olav Ways into Nidaros are walkable once the snow is off the Dovre passes, and the hostels along them open for the season. Walkers arrive at the cathedral all summer, thickest in the week before Olsok. Source ↗
- Nature
Aurora season
15 Sep – 31 Mar · usuallyFar enough south that it takes an active night rather than any dark one, but on those nights the lights are visible from the Bymarka hills fifteen minutes out of the centre. Coastal cloud is the usual spoiler.
Nearby, and something's on
Within 300 km of Trondheim — a day trip or a short hop — with something on this month. Never part of the comfort score.
Where is Trondheim?
Trondheim in September — FAQ
- Is September a good time to visit Trondheim?
- September in Trondheim: cool, rainy, with clean air — a great time to visit. It ranks #5 of 12 months for Trondheim on SeasonMap's comfort score (71/100).
- What is the weather like in Trondheim in September?
- In September, Trondheim averages a daily high of 14.2°C and a low of 7.5°C, with about 121.1 mm of rain over roughly 17.8 rainy days.
- What is the air quality in Trondheim in September?
- Trondheim has a mean US Air Quality Index of about 27 in September.
Other months in Trondheim
Compare Trondheim in September
Warmer or cooler than Trondheim in September
Similar destinations in Northern Europe — September
Within 300 km: Åre's Are autumn market around 20–30 Sep, and Geiranger's Dalsnibba and Eagle Road open around 20 May – 5 Nov.