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September Weather in Karis, Finland

Last updated: August 23, 2025

In Karis, Finland, the average temperature in September is a mild 13°C (55°F). Expect cool nights with temperatures dipping to a minimum of 2°C (36°F), while daytime highs can reach a comfortable 21°C (69°F). Be prepared for the possibility of rain, as 71 mm (2.8 in) of precipitation may fall over 13 days. With an average humidity of 87%, it's advisable to wear breathable clothing to stay comfortable throughout your stay.

September Temperature in Karis

In September in Karis, the average temperature is 13°C (55°F). Maximums can reach 21°C (69°F), while minimums can drop to as low as 2°C (36°F). Travelers should pack layers to stay comfortable during varying weather conditions.

September Weather in Karis: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Karis, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Karis, September typically has an average temperature of 13°C (55°F), with highs reaching up to 21°C (69°F) and lows dropping to around 2°C (36°F).
JanFebMarAprMayJunJulAugSepOctNovDec302832394860646355474033
Data source: Temperature data for Karis generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Karis

In Karis in September, the total precipitation amount is 71 mm (2.8 in) occurring over the course of 13 days.

September Precipitation Trends in Karis

The chart displays monthly precipitation patterns in Karis, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Karis, September typically receives around 71 mm (2.8 inches) of precipitation spread over approximately 13 days.
JanFebMarAprMayJunJulAugSepOctNovDec6050553647467386711107680
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Karis

In Karis in September, humidity is 87%. With an average temperature of 13°C (55°F), this humidity feels like a heavy blanket wrapping around you, making travel sluggish and slightly uncomfortable, as each step seems to cling to the damp air.

September Average Humidity in Karis

This chart illustrates the average monthly humidity levels in Karis, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Karis is approximately 87%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec92%91%90%87%76%80%80%83%87%90%91%90%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Karis

In Karis in September, the maximum UV index reaches 4, which corresponds to a moderate Exposure Category. With a time to burn of 30 minutes, it’s important to take precautions to protect your skin. You can find more details in the Hourly UV Index in Karis for better planning.

Maximum UV Index Levels in Karis for September

The chart shows the monthly maximum UV Index (UVI) for Karis in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Karis typically reaches 4, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec113457754211
Data source: Karis September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How September Weather in Karis Compares to Other Months

Weather in Karis varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Karis, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Karis, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-1°C (30°F)60 mm (2.3 inches)92%low
February Weather-2°C (28°F)50 mm (2.0 inches)91%low
March Weather0°C (32°F)55 mm (2.2 inches)90%moderate
April Weather4°C (39°F)36 mm (1.4 inches)87%moderate
May Weather9°C (48°F)47 mm (1.9 inches)76%moderate
June Weather15°C (60°F)46 mm (1.8 inches)80%high
July Weather18°C (64°F)73 mm (2.9 inches)80%high
August Weather17°C (63°F)86 mm (3.4 inches)83%moderate
September Weather13°C (55°F)71 mm (2.8 inches)87%moderate
October Weather8°C (47°F)110 mm (4.3 inches)90%low
November Weather5°C (41°F)76 mm (3.0 inches)91%low
December Weather1°C (33°F)80 mm (3.1 inches)90%low

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