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September Weather in Harjavalta, Finland

Last updated: August 23, 2025

In Harjavalta, Finland, the average temperature for September hovers around 11°C (53°F), making it a mild time of year. Expect temperatures to dip as low as -1°C (30°F) and rise to a maximum of 24°C (76°F). During this month, precipitation totals approximately 65 mm (2.6 in) spread over 12 days, contributing to a lush landscape. The average humidity stands at a notably high 86%, adding to the season’s character.

September Temperature in Harjavalta

In September in Harjavalta, the average temperature is 11°C (53°F), with maximums reaching up to 24°C (76°F) and minimums dropping as low as -1°C (30°F). Travelers should be prepared for a wide range of temperatures during this month, making layering essential for outdoor activities.

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

The chart illustrates September temperature patterns in Harjavalta, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Harjavalta, September typically has an average temperature of 11°C (53°F), with highs reaching up to 24°C (76°F) and lows dropping to around -1°C (30°F).
JanFebMarAprMayJunJulAugSepOctNovDec272531395061646152433730
Data source: Temperature data for Harjavalta 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 Harjavalta

In Harjavalta in September, the precipitation amount is 65 mm (2.6 in) over the course of 12 days.

September Precipitation Trends in Harjavalta

The chart displays monthly precipitation patterns in Harjavalta, 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 Harjavalta, September typically receives around 65 mm (2.6 inches) of precipitation spread over approximately 12 days.
JanFebMarAprMayJunJulAugSepOctNovDec434043384857909665755564
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Harjavalta

In Harjavalta in September, humidity is 86%. With an average temperature of 11°C (53°F), this humidity feels like a heavy blanket that dampens the air, making traveling uncomfortable and a bit stifling.

September Average Humidity in Harjavalta

This chart illustrates the average monthly humidity levels in Harjavalta, 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 Harjavalta is approximately 86%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec92%90%89%85%77%78%78%79%86%90%91%89%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Harjavalta

In Harjavalta 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 Harjavalta, you can check the information here.

Maximum UV Index Levels in Harjavalta for September

The chart shows the monthly maximum UV Index (UVI) for Harjavalta 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 Harjavalta typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec113456653211
Data source: Harjavalta 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 Harjavalta Compares to Other Months

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

This table compares monthly weather conditions in Harjavalta, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-3°C (27°F)43 mm (1.7 inches)92%low
February Weather-4°C (25°F)40 mm (1.6 inches)90%low
March Weather-1°C (31°F)43 mm (1.7 inches)89%moderate
April Weather4°C (40°F)38 mm (1.5 inches)85%moderate
May Weather10°C (50°F)47 mm (1.9 inches)77%moderate
June Weather16°C (61°F)57 mm (2.3 inches)78%high
July Weather18°C (64°F)90 mm (3.5 inches)78%high
August Weather16°C (61°F)96 mm (3.8 inches)79%moderate
September Weather11°C (53°F)65 mm (2.6 inches)86%moderate
October Weather6°C (44°F)75 mm (2.9 inches)90%low
November Weather3°C (37°F)55 mm (2.2 inches)91%low
December Weather-1°C (30°F)64 mm (2.5 inches)89%low

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