Jämsä Weather in September
September in Jämsä brings moderate temperatures, with highs of 15°C (59°F) and nights dropping to 7°C (45°F). Rainfall is on the higher side this month, averaging around 64 mm (2.5 in), so keep a rain jacket handy.
Rainfall in Jämsä in September
Expect around 17 days of rain based on historical data, with 64 mm (2.5 in) average. Expect plenty of grey, overcast days rather than intense storms. The rain rarely amounts to much on any given day.
Temperature in Jämsä in September
Jämsä in September gets highs of 15°C (59°F) during the day and drops to 7°C (45°F) at night. A light jacket or extra layer can be useful, especially outside the warmest hours of the day. With overnight lows of 7°C (45°F), nights are cold. The cold air does make for deep, comfortable sleep if you have enough blankets.Our weather planner can help you find worldwide destinations with pleasant weather during this period. June, July and August typically offer the best weather for Jämsä.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Finland, check out our Jämsä's climate page.
Jämsä Temperature in September
Min Temperature
7°C (45°F)
Max Temperature
15°C (59°F)
Chance of Rain
57%
Precipitation
64 mm (2.5 in)
Rainy days
17 days
Daily Historical Temperatures
50-year average (1976-2025)
Based on our historical records, temperatures in Jämsä typically drop from around 16°C (61°F) at the start of September to approximately 10°C (50°F) by the end. Nights are cold, with lows typically ranging from 4°C (39°F) to 9°C (48°F).
Average temperatures in September
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
Historical weather for Jämsä in September
Browse day-by-day weather records for Jämsä spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Jämsä historical weather extremes in September
Based on 26 years of weather observations (1999-2025), these are the most extreme conditions recorded in Jämsä.
- The hottest September day on record in Jämsä reached 26°C (79°F) (September 5, 2024).
- On September 23, 2014, Jämsä saw its coldest September day with temperatures maxing out at 3°C (37°F).
- The coldest night in September in Jämsä was on September 25, 2001, with a minimum of -4°C (25°F).
- The heaviest September precipitation occurred on September 29, 2016, when 24 mm (0.9 in) of precipitation fell.
Best Places in Finland in September
Find out more about the weather in Finland and which places have the best travel conditions in this month. See all of Finland in September →
perfect weather
pleasant
tolerable
unpleasant
poor
What to Wear in Jämsä in September
The weather can swing between comfortable and chilly in September, so flexibility is key. Pack a variety of tops, at least one warm layer, and both shorts and long pants. This gives you options no matter what the day brings. Wet weather is likely, so pack waterproof gear for multiple rainy days.What To Do in Jämsä in September
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Finland, check out our Jämsä's climate page.
See the full Jämsä climate overview or explore weather in Finland.
