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September Weather in Yli-Ii, Finland

Last updated: August 23, 2025

In September, the average temperature in Yli-Ii, Finland hovers around 9°C (49°F). Expect a chilling minimum of -5°C (24°F) and a pleasant maximum of 24°C (75°F). During this time, precipitation reaches approximately 76 mm (3.0 in) spread over 12 days, while the air maintains a high humidity of 90%.

September Temperature in Yli-Ii

In September in Yli-Ii, the average temperature is 9°C (49°F), with maximums reaching up to 24°C (75°F) and minimums dropping as low as -5°C (24°F). Travelers should be prepared for a wide range of temperatures, making layering essential for comfort during their stay.

September Weather in Yli-Ii: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Yli-Ii, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Yli-Ii, September typically has an average temperature of 9°C (49°F), with highs reaching up to 24°C (75°F) and lows dropping to around -5°C (24°F).
JanFebMarAprMayJunJulAugSepOctNovDec181624334557635748393023
Data source: Temperature data for Yli-Ii 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 Yli-Ii

In Yli-Ii in September, the total precipitation amount is 76 mm (3.0 in), occurring over the course of 12 days.

September Precipitation Trends in Yli-Ii

The chart displays monthly precipitation patterns in Yli-Ii, 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 Yli-Ii, September typically receives around 76 mm (3.0 inches) of precipitation spread over approximately 12 days.
JanFebMarAprMayJunJulAugSepOctNovDec454346415166779576866763
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Yli-Ii

In Yli-Ii in September humidity is 90%. With an average temperature of 9°C (49°F), this humidity feels like a chilly dampness that clings to your skin, making outdoor activities less enjoyable and necessitating extra layers to stay warm and comfortable while traveling.

September Average Humidity in Yli-Ii

This chart illustrates the average monthly humidity levels in Yli-Ii, 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 Yli-Ii is approximately 90%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec100%98%95%87%81%77%79%84%90%95%95%99%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Yli-Ii

In Yli-Ii 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 Yli-Ii, you can check the information here.

Maximum UV Index Levels in Yli-Ii for September

The chart shows the monthly maximum UV Index (UVI) for Yli-Ii 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 Yli-Ii typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec112346643211
Data source: Yli-Ii 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 Yli-Ii Compares to Other Months

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

This table compares monthly weather conditions in Yli-Ii, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-8°C (18°F)45 mm (1.8 inches)100%low
February Weather-9°C (17°F)42 mm (1.7 inches)98%low
March Weather-4°C (25°F)46 mm (1.8 inches)95%low
April Weather1°C (34°F)41 mm (1.6 inches)87%moderate
May Weather7°C (45°F)51 mm (2.0 inches)81%moderate
June Weather14°C (58°F)66 mm (2.6 inches)77%high
July Weather17°C (63°F)77 mm (3.0 inches)79%high
August Weather14°C (58°F)95 mm (3.7 inches)84%moderate
September Weather9°C (49°F)76 mm (3.0 inches)90%moderate
October Weather4°C (39°F)86 mm (3.4 inches)95%low
November Weather-1°C (30°F)67 mm (2.6 inches)95%low
December Weather-5°C (23°F)63 mm (2.5 inches)99%low

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