Helsinki Weather in September

With daytime temperatures of 16°C (61°F) and nighttime lows of 8°C (46°F), September in Helsinki brings moderate temperatures during the day. Do keep in mind that quite a bit of rainfall is typical. Around 64 mm (2.5 in) falls on average.

Rainfall in Helsinki in September

Looking at the last 30 years, the data shows about 17 days with rain, averaging 64 mm (2.5 in) for the month. With rain spread across many days but low totals, showers are typically short and light rather than heavy.

Temperature in Helsinki in September

September in Helsinki brings typical temperatures with highs around 16°C (61°F) and lows of 8°C (46°F). Conditions are often most pleasant around the middle of the day. At 8°C (46°F) overnight, it gets properly cold after dark. On the bright side, cold nights tend to make for excellent sleeping conditions.

Sunshine in Helsinki in September

The area enjoys a moderate level of sunlight, with around 151 hours. It's a good balance between sunny and cloudy days.

Wind Speed in Helsinki in September

Wind speeds average 3 m/s (6 knots) during September. At this speed, light breezes keep leaves and small twigs in gentle motion while the wind also provides natural cooling. Since this is an average, some days are more tranquil while others have more persistent light winds that are more noticeable.

Average water temperature in September

The water temperature is 13°C (55°F) — chilly, but perfectly fine for a swim if you're not too sensitive to cold water. A short wetsuit can make longer sessions more comfortable.

For Helsinki itself, June, July and August generally stand out with the best circumstances. If you're seeking pleasant, dry and sunny weather somewhere else in the world, our weather planner can help you explore other options.

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For a detailed overview over the year and the best time to visit Finland, check out our Helsinki's climate page.

Helsinki Temperature in September

Min Temperature 8°C (46°F)  

Max Temperature 16°C (61°F)  

Water Temperature 13°C (55°F)  

Chance of Rain 57%  

Precipitation 64 mm (2.5 in)  

Rainy days 17 days  

Humidity 84%  

Windspeed 3 m/s (6 knots)  

Sunshine 151 hours  

Percentage Sunshine  

Daily Historical Temperatures

50-year average (1976-2025)

Based on our historical records, temperatures in Helsinki typically drop from around 17°C (63°F) at the start of September to approximately 12°C (54°F) by the end. Nights are cold, with lows typically ranging from 5°C (41°F) to 10°C (50°F).

Average temperatures in September

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Daily Historical Precipitation

50-year average (1976-2025)

Average daily rainfall for each day of the month based on long-term records.

Average precipitation in September

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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

‹ January February March April May June July August September October November December ›

Historical weather for Helsinki in September

Browse day-by-day weather records for Helsinki spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.

Historical weather Temperatures Precipitation

‹ 2026 2025 2024 2023 2022 2021 2020 2019 2018 2017 2016 2015 2014 2013 2012 2011 2010 2009 2008 2007 2006 2005 2004 2003 2002 2001 2000 1999 1998 1997 1996 1995 1994 1993 1992 1991 1990 1989 1988 1987 1986 1985 1984 1983 1982 1981 1980 1979 1978 1977 ›

‹ January February March April May June July August September October November December ›

Helsinki historical weather extremes in September

The extremes listed below come from historical weather data collected in Helsinki from 1976 through 2025.

• Helsinki recorded its highest September temperature of 27°C (81°F) on September 5, 2024.
• Helsinki experienced its chilliest September day on September 23, 2014, reaching only 5°C (41°F).
• Helsinki registered its coldest September night on September 30, 1993, with temperatures dropping to -6°C (21°F).

What to Wear in Helsinki in September

Pleasant temperatures in September mean you can pack light but flexibel pieces. Think cotton t-shirts, comfortable walking shorts, and one warmer layer for evenings. A light sweater or denim jacket works well. Rain gear is recommended, you can expect wet weather on multiple days. With water temperatures around 13°C (55°F), the water is quite cold for swimming. You can skip the swimwear unless you're particularly tough. Bring sunglasses since you'll have some sunny periods throughout the month

What To Do in Helsinki in September

We rated the following activities from 1 (least suitable) to 10 (best) to do.

Swimming

5/10

Cycling

6/10

Walking

6/10

Barbeque

6/10

Camping

4/10

Outdoor sports

10/10

Select a Month

Check the conditions for any month of the year.

• January
• February
• March
• April

• May
• June
• July
• August

• September
• October
• November
• December

For a detailed overview over the year and the best time to visit Finland, check out our Helsinki's climate page.

More climate data for Helsinki

Temperature Rainfall Sunshine Humidity Wind Speed Water Temp

See the full Helsinki climate overview or explore weather in Finland.