Trondheim weather in September
Temperature, sea and sunshine in September: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in September
Fair
Best time to visit: June – August
What is the weather like in Trondheim in September?
In September, Trondheim is cool: daytime highs average 14 °C, and nights cool down to about 8 °C. The sea averages 12.8 °C – swimming is only for the hardy. Expect around 5 hours of sunshine a day. It rains often – on about 15 days, adding up to 106 mm. All in all, September is a so-so month for a holiday in Trondheim.
September compared
How the weather changes from August to October. Tap a month to open it.
| AugustAug | SeptemberSep | OctoberOct | |
|---|---|---|---|
| Score | 66 | 43 | 6 |
| Day | 18° | 14° | 8° |
| Night | 11° | 8° | 2° |
| Sea | 14° | 13° | 11° |
| Sun | 6 h | 5 h | 3 h |
| Rain days | 15 | 15 | 16 |
More details for September
- Daylight
- 13 h 9 min06:39 – 19:48
- UV index
- 2 · lowclear sky, noon (estimate)All months
- Muggy days
- 0 daysdew point 18 °C or moreAll months
- Wind
- 13 km/haverage daily peakAll months
- Cloud cover
- 73 %on averageAll months
- Hot days
- 0 days30 °C or more
- Snow days
- 0 days1 cm or more of fresh snowAll months
- Time zone
- UTC+2Europe/Oslo
How the score comes together
- Temperatureweight 50 %63 %
- Sunshineweight 20 %25 %
- Few rainy daysweight 30 %21 %
Each factor is rated from 0 to 100 % and weighted for the travel style “City break”.
What to pack in September
- A jumper for the evenings
- Rain jacket or umbrella
Trondheim in September: quick answers
Is Trondheim hot in September?
No. In September, Trondheim is cool: daytime highs average 14 °C and nights drop to about 8 °C.
Can you swim in Trondheim in September?
Only if you don't mind cold water: in September the sea averages just 12.8 °C. Comfortable swimming temperatures are not reached at any time of year.
Does it rain much in Trondheim in September?
It rains often – on about 15 days, adding up to 106 mm.
Trondheim month by month
The whole year in TrondheimAll destinations: NorwayWhere to go in SeptemberSea temperature in September
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, WMO 1991–2020 (NOAA NCEI), GeoNames (CC BY 4.0). Sources & licences