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Turku in September: Weather, Average temperature and Climate

Planning a trip and want to know what the weather in Turku in September will be like? Take a look at our weather guide for Turku, based on historical data.
Check flight prices to Turku on Avionero:
September

Weather in Turku in September 2025

OK Weather
Mild
🌧️
Rainy
🌊
Cold water
If you plan to visit Turku in September, the weather is typically alright, with an average high temperature of +59°F during the day and approximately 6 sunny days. Expect some rainy, though, as there are typically 15 rainy days in the month and around 56 mm of precipitation. The weather is changeable so you may have to pack for every eventuality. Search flights in one click on Avionero.

Average weather

☀️
+59°F
Avg. max. temperature
+27°F
Min.
+75°F
Max.
56 mm
Total precipitation
82%
Avg. humidity
3 m/s
Avg. wind
6 ☀️
Sunny Days
9 ⛅️
Cloudy
15 🌦
Rainy
Our opinion: Turku has OK weather in September.

Average temperature in Turku in September

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

Going from a maximum of +72°F during the day to a minimum of +37°F during the night, the temperature in September averages around +64°F.

The average maximum temperature goes down 11% by the end of the month, compared with the beginning of the month, from +64°F to +61°F.

Is Turku warm or cold in September?

Turku is typically mild in September.

Maximum temperatures go down compared to the previous month from +68°F to +59°F. The minimum temperature also goes down from +54°F to +46°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 Turku:

Water temperature in Turku in September

Water in Turku in September is Cold. It varies from +39°F to +66°F, with an average of +53°F. This is almost similar to the air temperature, which averages +59°F.

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

The warmest water temperatures in Turku are reached in August, when the average sea temperature rises to +58°F. The coldest water temperatures are in February, with an average of +32°F.

Can you swim in Turku in September?

We would not recommend swimming in Turku in September, the water is very cold (+53°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 Turku in September

Turku weather looks like this, on average, in September and the surrounding months.
AugustSeptemberOctober
Avg. temperature
+68°F+59°F+48°F
Min. temperature
+37°F+27°F+10°F
Max. temperature
+88°F+75°F+63°F
Rainfall
75 mm56 mm60 mm
Wind
3 m/s3 m/s4 m/s
Avg. water temperature
+58°F+53°F+46°F
Humidity
77%82%85%
Air pressure
1011 HPa1011 HPa1011 HPa
Sunny days
764
Cloudy days
6911
Rainy days
171515
Snowy days
001

September weather is still as ok as in August. It’s getting colder in September. From +68°F in the day, the average maximum temperature lowers to +59°F. As September arrives, the amount of rainfall goes down. On average, the rainfall volume decreases from 75 mm to 56 mm. Humidity rises from 77% to 82%. The average wind speed doesn’t change much during September, staying around 3 m/s. The days becoming less sunny, going from 7 sunny days in August to 6 in September.

October brings much the same weather, it remains ok.

Wind

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

The average wind speed is 3 m/s getting up to 6 m/s which is a medium breeze. You can feel it, especially getting out of the water.

The average wind speed in Turku is gradually increasing during September, going from 2 m/s to 4 m/s over the course of the month.

Rain

Amount of rainfall in mm during September in Turku based on historical data.
Last Year
Historical Data
Typically, there is a 40% chance of rain on an average day in September, with total rainfall of approximately 49 mm. The maximum amount of rainfall per day is around 9 mm, which is considered light rain. September is a pretty wet month with over 12 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:
Turku wettest month is August, where a typical day has a 55% chance of precipitation and 75 mm of rainfall per day. February, on the other hand, is the driest month with a mere 7% chance of precipitation and 8 mm of rainfall per day.

How was the weather last September in Turku?

This is the weather in Turku in September 2023:
1 September
🌧️
+65°F
2 September
☀️
+61°F
3 September
☁️
+65°F
4 September
☁️
+66°F
5 September
☁️
+66°F
6 September
☀️
+63°F
7 September
☀️
+66°F
8 September
☀️
+71°F
9 September
☀️
+67°F
10 September
☁️
+70°F
11 September
☁️
+65°F
12 September
☁️
+66°F
13 September
☀️
+64°F
14 September
☀️
+62°F
15 September
☀️
+61°F
16 September
☁️
+65°F
17 September
☀️
+59°F
18 September
☀️
+59°F
19 September
☀️
+64°F
20 September
☀️
+62°F
21 September
☀️
+68°F
22 September
☀️
+69°F
23 September
☀️
+63°F
24 September
☁️
+60°F
25 September
☀️
+62°F
26 September
☁️
+62°F
27 September
☁️
+64°F
28 September
☁️
+64°F
29 September
☁️
+63°F
30 September
🌧️
+60°F
In September 2023 Turku had 16 sunny days, 12 cloudy days, and 2 rainy days. The average maximum temperature was +64°F, with an absolute maximum of +72°F and a minimum of +59°F. The average humidity was 87%, with a maximum of 100% and a minimum of 54%. The average wind speed was 3 m/s, with a maximum of 12 m/s and a minimum of 0 m/s.
Are you planning a trip in September?

Climate Change Over the Years

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

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

The average temperature was the lowest in 1987 (+43°F) and the highest in 2020 (+52°F). The driest year was 2003 with only 300 mm of rainfall, and the wettest year was 2020 with 615 mm.

FAQ

Frequently asked questions about the weather in Turku in September:

Is September a good time to visit Turku?

It’s always a good time to visit Turku, 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 Turku in September?

September has mild temperatures in Turku. 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 Turku in September?

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

Is Turku rainy in September?

Turku 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 Turku in September?

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

Other cities in Finland

Check out the weather for other cities in Finland.

Monthly weather in Turku

Source of the data

For this page, we’ve looked at the typical weather in Turku, 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.