Norway
Trondheim in September: weather, sea & travel advice
This month's data profile
Rain shapes the decision
Trondheim in September is climatically mixed. The average daily high is around 13 °C, and the sea is about 13 °C. With about 18 rainy days it is very wet.
Historical monthly averages, not a weather forecast. Individual days and years can differ substantially.
Rank among 12 monthly averages
25/100 · #5
Warmth
#4
Dryness
#3
Sun
#6
Sea warmth
#3
Published best categories: none
Trondheim · SeptemberPhoto: David Stanley from Nanaimo, Canada · CC BY 4.0Climate facts
- Average high
- 13 °C
- Average low
- 7 °C
- Sea
- 13 °C
- Rainy days (est.)
- 18 rainy days (est.)
- Sun (est.)
- 3 h/day
- Humidity
- 88 %
Climate evidence with direct month comparison
The highlighted row is the selected month. Precipitation total and rainy days are separate monthly averages.
| Month | Avg high °C | Avg low °C | Rainy days (est.) | Precipitation mm | Sun h/day (est.) | Humidity % | Wind m/s | Sea °C | Score |
|---|---|---|---|---|---|---|---|---|---|
| August | 16 | 10 | 20 | 149 | 4.4 | 86 | 0.6 | 14 | 34 |
| September (selected) | 13 | 7 | 18 | 136 | 2.7 | 88 | 0.7 | 13 | 25 |
| October | 7 | 2 | 20 | 136 | 1.2 | 92 | 0.8 | 11 | 13 |
How do the previous and next months compare?
Baseline: September (25/100)
Positive and negative values show the change from the selected month.
| Score Δ | Average high Δ | Average low Δ | Rainy days Δ | Rain Δ | Sun Δ | Humidity Δ | Wind Δ | Sea Δ | |
|---|---|---|---|---|---|---|---|---|---|
| August | +9 | +3.7 °C | +3 °C | +2.7 | +13.1 mm | +1.7 h | -2.1 % | -0.1 m/s | +1 °C |
| October | -12 | -6.1 °C | -4.6 °C | +2 | -0.1 mm | -1.5 h | +4.1 % | +0.1 m/s | -1.9 °C |
All twelve months in context
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Where to stay in Trondheim
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Useful next decisions
Frequently asked questions
How warm is Trondheim in September?
The average daily high is around 13 °C, with an average daily low of about 7 °C.
Can you swim in Trondheim in September?
The sea is about 13 °C (cold).
Does it rain a lot in Trondheim in September?
The curated estimate is about 18 rainy days per month, not a directly measured long-term average. Total precipitation averages around 136 mm for the month. A rainy day does not mean all-day rain.
When is the best time to visit Trondheim?
No month in Trondheim reaches the threshold for a clear recommendation in the climate score; the month comparison above shows the differences.