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Oslo in September: Weather, Average temperature and Climate

Take a look at past year’s weather for Oslo in September and see if it is worth visiting.
Check flight prices to Oslo on Avionero:
September

Weather in Oslo in September 2025

OK Weather
Mild
🌧️
Rainy
🌊
Cold water
Oslo in September usually sees fair weather conditions, with an average daily high temperature of +61°F and roughly 3 sunny days. However, you should prepare for about 15 rainy days with an average precipitation of 94 mm. The weather is changeable so pack for every eventuality. Search flights in one click on Avionero.

Average weather

☀️
+61°F
Avg. max. temperature
+30°F
Min.
+79°F
Max.
94 mm
Total precipitation
75%
Avg. humidity
2 m/s
Avg. wind
3 ☀️
Sunny Days
11 ⛅️
Cloudy
15 🌦
Rainy
Our opinion: Oslo has OK weather in September.

Average temperature in Oslo in September

Here are the expected maximum, average and minimum temperatures in Oslo for September based on the historical data.
Last Year
Historical Data

The temperature in September is +66°F on average, with a range between a maximum of +77°F during the day and a minimum of +41°F at night.

The average maximum temperature goes down 20% by the end of the month, compared with the beginning of the month, from +72°F to +64°F.

Is Oslo warm or cold in September?

Oslo is typically mild in September.

Maximum temperatures go down compared to the previous month from +70°F to +61°F. The minimum temperature also goes down from +54°F to +48°F.

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 +56°F to +64°F, with an average of +60°F. This is almost similar to the air temperature, which averages +61°F.

The water temperature in September is one of the warmest of the entire year:

The warmest water temperatures in Oslo are reached in August, when the average sea temperature rises to +64°F. The coldest water temperatures are in March, with an average of +37°F.

Can you swim in Oslo in September?

We would not recommend swimming in Oslo in September, the water is very cold (+60°F on average). Consider swimming only if you are an experienced cold-water swimmer with proper gear.
🦭
Cold
Below +61°F
🏄‍♂️
Fresh
61°F - 70°F
🏊
Comfortable
70°F - 77°F
👙
Warm
77°F - 82°F
🔥
Very warm
+82°C and up
You will need a full-body wetsuit, cap, gloves, a warm change of clothes, and a hot drink ready for after your swim.

Climate in Oslo in September

Oslo weather looks like this, on average, in September and the surrounding months.
AugustSeptemberOctober
Avg. temperature
+70°F+61°F+50°F
Min. temperature
+41°F+30°F+19°F
Max. temperature
+91°F+79°F+66°F
Rainfall
108 mm94 mm114 mm
Wind
2 m/s2 m/s2 m/s
Avg. water temperature
+64°F+60°F+53°F
Humidity
72%75%79%
Air pressure
1010 HPa1011 HPa1010 HPa
Sunny days
232
Cloudy days
111112
Rainy days
181515
Snowy days
001

September typically has worse weather conditions compared to August. It’s getting colder in September. From +70°F in the day, the average maximum temperature lowers to +61°F. 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

Wind speed in Oslo in September based on historical data.
Last Year
Historical Data

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

Amount of rainfall in mm during September in Oslo based on historical data.
Last Year
Historical Data
A chance of rain on a typical day in September stands at 37%, leading to total precipitation of around 106 mm. The maximum amount of rainfall per day is around 34 mm, which is moderate rain. September is a pretty wet month with over 11 rainy days, so don’t forget to pack an umbrella, raincoat, and a pair of wellies.
Here’s how September is compared with other months in the amount of precipitation, total mm:
Oslo wettest month is October, where a typical day has a 48% chance of precipitation and 114 mm of rainfall per day. March, on the other hand, is the driest month with a mere 13% chance of precipitation and 26 mm of rainfall per day.

How was the weather last September in Oslo?

This is the weather in Oslo in September 2023:
1 September
☁️
+72°F
2 September
☁️
+69°F
3 September
☁️
+65°F
4 September
☀️
+77°F
5 September
☀️
+77°F
6 September
☁️
+69°F
7 September
☁️
+67°F
8 September
☁️
+67°F
9 September
☁️
+68°F
10 September
☁️
+73°F
11 September
☁️
+66°F
12 September
☁️
+70°F
13 September
☀️
+63°F
14 September
☁️
+59°F
15 September
☁️
+64°F
16 September
🌧️
+60°F
17 September
☁️
+61°F
18 September
🌧️
+61°F
19 September
🌧️
+62°F
20 September
☁️
+62°F
21 September
🌧️
+65°F
22 September
🌧️
+61°F
23 September
☁️
+62°F
24 September
☀️
+60°F
25 September
🌧️
+62°F
26 September
☁️
+64°F
27 September
☁️
+65°F
28 September
☁️
+64°F
29 September
☁️
+63°F
30 September
☀️
+65°F
In September 2023 Oslo had 5 sunny days, 19 cloudy days, and 6 rainy days. The average maximum temperature was +66°F, with an absolute maximum of +77°F and a minimum of +59°F. The average humidity was 85%, with a maximum of 100% and a minimum of 44%. The average wind speed was 2 m/s, with a maximum of 7 m/s and a minimum of 0 m/s.
Are you planning a trip in September?

Climate Change Over the Years

This is how Oslo climate has changed over the last 43 years.

The climate in Oslo in September has not changed that much over the last 43 years.

The average temperature was the lowest in 1985 (+46°F) and the highest in 2020 (+54°F). The driest year was 1981 with only 527 mm of rainfall, and the wettest year was 2020 with 2467 mm.

FAQ

Frequently asked questions about the weather in Oslo in September:

Is September a good time to visit Oslo?

It’s always a good time to visit Oslo, but the weather is changeable in September, so plan a mix of indoor and outdoor activities and exploring, and pack for every eventuality.

Can you sunbathe in Oslo in September?

September has mild temperatures in Oslo. Not ideal for sunbathing, but still good for daytime outdoor activities, but plan for cool evenings. Pack a light jacket and shorts!

Can you swim in Oslo in September?

Swimming in Oslo in September is challenging and not recommended for inexperienced swimmers or without proper equipment and preparation.

Is Oslo rainy in September?

Oslo is often rainy in September. You may get a bit damp when outside, so pack an umbrella, and maybe even a raincoat.

Is it sunny in Oslo in September?

Usually, it’s not very sunny in Oslo in September, often it’s pretty cloudy. Pack for any eventuality; layering can help reduce the number of bulky items needed.

Other cities in Norway

Check out the weather for 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.