September Weather in Posio, Finland

Last updated: August 23, 2025

In September, the average temperature in Posio, Finland is a cool 7°C (46°F). Visitors can experience a range of temperatures, with a minimum dipping to -5°C (23°F) and a pleasant maximum reaching 21°C (71°F). Precipitation averages 82 mm (3.2 in) over 14 days, and the air is quite moist, boasting an average humidity of 91%. Perfect for those who enjoy a brisk, refreshing climate!

September Temperature in Posio

In September in Posio, the average temperature is 7°C (46°F), with maximums reaching 21°C (71°F) and minimums dipping as low as -5°C (23°F). This varied weather makes it important to pack layers and be prepared for both warmth and chill while exploring the region.

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

The chart illustrates September temperature patterns in Posio, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Posio, September typically has an average temperature of 7°C (46°F), with highs reaching up to 21°C (71°F) and lows dropping to around -5°C (23°F).
JanFebMarAprMayJunJulAugSepOctNovDec141321314154595445352720
Data source: Temperature data for Posio 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 Posio

In Posio in September, the precipitation amount is 82 mm (3.2 in) spread over 14 days.

September Precipitation Trends in Posio

The chart displays monthly precipitation patterns in Posio, 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 Posio, September typically receives around 82 mm (3.2 inches) of precipitation spread over approximately 14 days.
JanFebMarAprMayJunJulAugSepOctNovDec4340444349857611082827158
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Posio

In Posio in September humidity is 91%. With an average temperature of 7°C (46°F), this humidity feels like a damp chill that seeps into your bones, making outdoor activities feel less invigorating and more exhausting, as the heavy air clings to your skin and makes every breath feel thicker.

September Average Humidity in Posio

This chart illustrates the average monthly humidity levels in Posio, 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 Posio is approximately 91%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec101%99%94%88%83%79%83%88%91%96%96%100%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Posio

In Posio in September, the maximum UV index is 3, which corresponds to a moderate Exposure Category. The time to burn is approximately 30 minutes. For more details on the hourly UV index in Posio, you can check the information here.

Maximum UV Index Levels in Posio for September

The chart shows the monthly maximum UV Index (UVI) for Posio 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 Posio typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec112356643211
Data source: Posio 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 Posio Compares to Other Months

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

This table compares monthly weather conditions in Posio, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-10°C (14°F)43 mm (1.7 inches)101%low
February Weather-10°C (14°F)40 mm (1.6 inches)99%low
March Weather-6°C (21°F)44 mm (1.7 inches)94%low
April Weather0°C (32°F)43 mm (1.7 inches)88%moderate
May Weather5°C (41°F)49 mm (1.9 inches)83%moderate
June Weather12°C (55°F)85 mm (3.4 inches)79%high
July Weather15°C (60°F)76 mm (3.0 inches)83%high
August Weather12°C (55°F)110 mm (4.3 inches)87%moderate
September Weather7°C (46°F)82 mm (3.2 inches)91%moderate
October Weather2°C (35°F)82 mm (3.2 inches)96%low
November Weather-3°C (27°F)71 mm (2.8 inches)96%low
December Weather-7°C (20°F)58 mm (2.3 inches)100%low

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