nomadseason

December Weather in Helena, United States

Last updated: June 24, 2025

In December, the average temperature in Helena, United States hovers around 12°C (54°F). However, be prepared for a temperature range that can dip as low as -5°C (23°F) and rise to a pleasant 26°C (80°F). Expect about 126 mm (4.9 in) of precipitation spread over 9 days, contributing to a notable average humidity of 88%.

December Temperature in Helena

In December in Helena, the average temperature is 12°C (54°F). The maximum can reach 26°C (80°F) and the minimum can be as low as -5°C (23°F). This variability makes Helena an ideal destination for travelers seeking both mild and cooler weather experiences.

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 12°C (54°F), with highs reaching up to 26°C (80°F) and lows dropping to around -5°C (23°F).
JanFebMarAprMayJunJulAugSepOctNovDec525761677580838279725854
Data source: Temperature data for Helena generated using information from the Copernicus Climate Change Service.
Choose your preferred temperature unit
The average of daily temperatures (24 hours) calculated across all days in the month.

December Precipitation in Helena

In Helena in December, the total precipitation amount is 126 mm (4.9 in) spread over a duration of 9 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 126 mm (4.9 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec831077888721031181061078953126
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

December Humidity in Helena

In Helena in December, humidity is 88%. With an average temperature of 12°C (54°F), this humidity feels like a thick, damp blanket, making traveling a bit uncomfortable as the air clings to your skin, causing you to sweat even in cooler weather.

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 88%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec85%82%80%76%73%74%80%79%83%77%84%88%
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.
JanFebMarAprMayJunJulAugSepOctNovDec479101111111110864
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 Weather11°C (52°F)83 mm (3.2 inches)85%moderate
February Weather14°C (58°F)107 mm (4.2 inches)82%high
March Weather16°C (62°F)78 mm (3.1 inches)80%very high
April Weather20°C (67°F)88 mm (3.4 inches)76%very high
May Weather24°C (76°F)72 mm (2.8 inches)73%extreme
June Weather27°C (80°F)103 mm (4.1 inches)74%extreme
July Weather28°C (83°F)118 mm (4.6 inches)80%extreme
August Weather28°C (82°F)106 mm (4.2 inches)79%extreme
September Weather26°C (80°F)107 mm (4.2 inches)83%very high
October Weather22°C (72°F)89 mm (3.5 inches)77%very high
November Weather14°C (58°F)53 mm (2.1 inches)84%high
December Weather12°C (54°F)126 mm (4.9 inches)88%moderate

Compare Helena's Climate with Cities Worldwide