September weather forecast
Trondheim, Norway

September sees a noticeable drop in temperatures, slipping from 6°C (42.8°F) to 12°C (53.6°F), as Trondheim starts to welcome autumn. Even the longest day in September is shorter than the shortest day in August, signifying the approach of shorter daylight hours. The declining temperatures and daylight hours are accompanied by the highest rainfall in the year, totalling 133mm (5.24"). Yet, despite the less inviting environment, the city dons a beautiful autumnal cloak, attracting a fair share of nature enthusiasts. The month ends with a noticeable chill in the air, hinting at the upcoming winter cold.

Temperature

The onset of September in Trondheim comes with a shift in the average high-temperature, falling from a comfortable 17°C (62.6°F) in August to a fresh 12°C (53.6°F). Trondheim's nighttime temperature in September falls to an average of 6°C (42.8°F).

Rainfall

The month with the most rainfall in Trondheim is September, when the rain falls for 24 days and typically aggregates up to 133mm (5.24") of precipitation.

Sea temperature

In September, the average sea temperature in Trondheim is 13.4°C (56.1°F).
Note: Swimming at temperatures less than 10°C (50°F) in 13.4°C (56.1°F) is feasible with the right swimsuit; if not, expect cold shock and breathlessness. A quick swim at 13°C (55.4°F) without adequate warmth can be discomforting.

Daylight

In September, the average length of the day in Trondheim is 12h and 59min.
On the first day of September, sunrise is at 06:04 and sunset at 20:31. On the last day of the month, sunrise is at 07:25 and sunset at 18:51 CEST.

Sunshine

The average sunshine in September is 3h.

UV index

In September, the average daily maximum UV index in Trondheim is 2. A UV Index of 2, and less, symbolizes a low health risk from exposure to the Sun's UV radiation for ordinary individuals.
Note: The maximum daily UV index of 2 in September interprets into the following recommendations:
Most people can stay in the Sun for up to 1 hour without burning, apart from children that always must be protected from sun exposure. Minimize direct exposure to the Sun during midday when its radiation is at its peak. Select sunglasses that boast both UVA and UVB protection to limit the adverse effects of the sun on the eyes.