Weather in Oslo in September 2025
Average weather
Average temperature in Oslo in September
Going from a maximum of +25°C during the day to a minimum of +5°C during the night, the temperature in September averages around +19°C.
The average maximum temperature goes down 20% by the end of the month, compared with the beginning of the month, from +22°C to +18°C.
Is Oslo warm or cold in September?
Oslo is typically mild in September.
Maximum temperatures go down compared to the previous month from +21°C to +16°C. The minimum temperature also goes down from +12°C to +9°C.
Pack a light jacket as it will be warm in the day and cool in the evenings.
Take a look at how September is compared to other months in Oslo:
Water temperature in Oslo in September
Water in Oslo in September is Cold. It varies from +13°C to +18°C, with an average of +15°C. This is almost similar to the air temperature, which averages +16°C.
The water temperature in September is one of the warmest of the entire year:
Can you swim in Oslo in September?
Climate in Oslo in September
| August | September | October | ||||
|---|---|---|---|---|---|---|
| Avg. temperature | ||||||
| +21°C | +16°C | +10°C | ||||
| Min. temperature | ||||||
| +5°C | -1°C | -7°C | ||||
| Max. temperature | ||||||
| +33°C | +26°C | +19°C | ||||
| Rainfall | ||||||
| 108 mm | 94 mm | 114 mm | ||||
| Wind | ||||||
| 2 m/s | 2 m/s | 2 m/s | ||||
| Avg. water temperature | ||||||
| +18°C | +15°C | +12°C | ||||
| Humidity | ||||||
| 72% | 75% | 79% | ||||
| Air pressure | ||||||
| 1010 HPa | 1011 HPa | 1010 HPa | ||||
| Sunny days | ||||||
| 2 | 3 | 2 | ||||
| Cloudy days | ||||||
| 11 | 11 | 12 | ||||
| Rainy days | ||||||
| 18 | 15 | 15 | ||||
| Snowy days | ||||||
| 0 | 0 | 1 | ||||
September typically has worse weather conditions compared to August. It’s getting colder in September. From +21°C in the day, the average maximum temperature lowers to +16°C. As September arrives, the amount of rainfall goes down. On average, the rainfall volume decreases from 108 mm to 94 mm. Humidity rises from 72% to 75%. The average wind speed doesn’t change much during September, staying around 2 m/s. The good news is there are likely to be more sunny days in September, from 2 to 3.
October brings much the same weather, it remains ok.
Wind
The average wind speed is 2 m/s getting up to 5 m/s which is a light breeze; barely moving the tree leaves.
The average wind speed in Oslo is gradually increasing during September, going from 2 m/s to 3 m/s over the course of the month.
Rain
How was the weather last September in Oslo?
Climate Change over Years
The climate in Oslo in September has not changed much over the last 43 years.
The average temperature was the lowest in 1985 (+8°C) and the highest in 2020 (+12°C). The driest year was 1981 with only 527 mm of rainfall, and the wettest year was 2020 with 2467 mm.
FAQ
Is September a good time to visit Oslo?
Can you sunbathe in Oslo in September?
Can you swim in Oslo in September?
Is Oslo rainy in September?
Is it sunny in Oslo in September?
Other cities in Norway
Monthly weather in Oslo
Source of the data
For this page, we’ve looked at the typical weather in Oslo, based on historical hourly weather data from January 1, 1979, to December 31, 2023.
For past dates, we show actual recorded data at the location at that time. Forecasts are based on recorded weather during that day of the year, averaged over the total years for which we have records (unless stated otherwise). The daily temperature is the highest recorded temperature in the shadow during that day.