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December Weather in Harjavalta, Finland

Last updated: August 23, 2025

In December, the average temperature in Harjavalta, Finland hovers around -1°C (30°F). Expect chilly days where temperatures can dip as low as -19°C (-3°F) and reach a maximum of 6°C (44°F). Prepare for wet weather, as 64 mm (2.5 in) of precipitation is likely over 12 days, accompanied by a high average humidity of 89%.

December Temperature in Harjavalta

In December in Harjavalta, the average temperature is -1°C (30°F), with maximums reaching 6°C (44°F) and minimums plunging to -19°C (-3°F). Be sure to pack warm clothing if you plan to travel during this chilly month.

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

The chart illustrates December 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, December typically has an average temperature of -1°C (30°F), with highs reaching up to 6°C (44°F) and lows dropping to around -19°C (-3°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.

December Precipitation in Harjavalta

In Harjavalta in December, the total precipitation amount is 64 mm (2.5 in) over the course of 12 days.

December Precipitation Trends in Harjavalta

The chart displays monthly precipitation patterns in Harjavalta, with values for each month alongside December’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how December’s conditions compare to those of other months. In Harjavalta, December typically receives around 64 mm (2.5 inches) of precipitation spread over approximately 12 days.
JanFebMarAprMayJunJulAugSepOctNovDec434043384857909665755564
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Harjavalta

In Harjavalta in December humidity is 89%. With an average temperature of -1°C (30°F), this humidity feels like a biting chill that wraps around you, making outdoor travel uncomfortable and brisk, as the cold air sharpens the dampness, leaving you feeling colder than the thermometer suggests.

December Average Humidity in Harjavalta

This chart illustrates the average monthly humidity levels in Harjavalta, with December’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In December, average humidity in Harjavalta is approximately 89%, 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 December generated using information from the Copernicus Climate Change Service.

December UV Index in Harjavalta

In Harjavalta in December, the maximum UV index is 1, which corresponds to a low Exposure Category. This means you have a time to burn of 45 minutes. For more details, you can check the Hourly UV Index in Harjavalta.

Maximum UV Index Levels in Harjavalta for December

The chart shows the monthly maximum UV Index (UVI) for Harjavalta in December, 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 December, the maximum UV index in Harjavalta typically reaches 1, which falls under the low exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec113456653211
Data source: Harjavalta December 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 December 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 December’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 December’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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