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December Weather in Helena, United States

Last updated: June 24, 2025

In December, the average temperature in Helena, United States hovers around 14°C (57°F). Be prepared for a range of temperatures, with the minimum dropping to -2°C (29°F) and the maximum soaring to 26°C (80°F). During this month, expect about 109 mm (4.3 in) of precipitation spread over 11 days, contributing to an average humidity of 87%.

December Temperature in Helena

In December in Helena, the average temperature is 14°C (57°F). The maximum can reach 26°C (80°F), while the minimum can be as low as -2°C (29°F). Travelers should be prepared for a wide range of temperatures and pack accordingly.

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

The chart illustrates December temperature patterns in Helena, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Helena, December typically has an average temperature of 14°C (57°F), with highs reaching up to 26°C (80°F) and lows dropping to around -2°C (29°F).
JanFebMarAprMayJunJulAugSepOctNovDec535964687580828279736056
Data source: Temperature data for Helena 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 Helena

In Helena in December, the precipitation amount is 109 mm (4.3 in), occurring over a span of 11 days.

December Precipitation Trends in Helena

The chart displays monthly precipitation patterns in Helena, 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 Helena, December typically receives around 109 mm (4.3 inches) of precipitation spread over approximately 11 days.
JanFebMarAprMayJunJulAugSepOctNovDec901048712013224617921815513456109
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Helena

In Helena in December humidity is 87%. With an average temperature of 14°C (57°F), this humidity feels like a thick blanket enveloping you, making every breath feel heavy and sticky, which can be quite challenging for travelers exploring the city.

December Average Humidity in Helena

This chart illustrates the average monthly humidity levels in Helena, 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 Helena is approximately 87%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec82%80%80%78%73%71%79%78%80%76%83%87%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Helena

In Helena in December, 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 Helena for better planning.

Maximum UV Index Levels in Helena for December

The chart shows the monthly maximum UV Index (UVI) for Helena 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 Helena typically reaches 4, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec589111111121110864
Data source: Helena 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 Helena Compares to Other Months

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

This table compares monthly weather conditions in Helena, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather12°C (53°F)90 mm (3.5 inches)82%moderate
February Weather15°C (59°F)104 mm (4.1 inches)80%very high
March Weather18°C (64°F)87 mm (3.4 inches)80%very high
April Weather20°C (68°F)120 mm (4.7 inches)78%extreme
May Weather24°C (76°F)132 mm (5.2 inches)73%extreme
June Weather27°C (81°F)246 mm (9.7 inches)71%extreme
July Weather28°C (82°F)179 mm (7.0 inches)79%extreme
August Weather28°C (82°F)218 mm (8.6 inches)78%extreme
September Weather26°C (79°F)155 mm (6.1 inches)80%very high
October Weather23°C (73°F)134 mm (5.3 inches)76%very high
November Weather15°C (60°F)56 mm (2.2 inches)83%high
December Weather14°C (57°F)109 mm (4.3 inches)87%moderate

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