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December Weather in Heidelberg, United States

Last updated: June 24, 2025

In December, the average temperature in Heidelberg, United States is a cool 11°C (53°F). Expect minimum temperatures to drop as low as -4°C (25°F), while the mercury can rise to a pleasant 27°C (81°F). With an average humidity of 87% and precipitation totaling 133 mm (5.3 in) over 12 days, be prepared for a mix of cool and damp weather.

December Temperature in Heidelberg

In December in Heidelberg, the average temperature is 11°C (53°F). Maximum temperatures can reach up to 27°C (81°F), while minimums can drop as low as -4°C (25°F). Be sure to pack layers to stay comfortable throughout the varying temperatures during your travels!

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

The chart illustrates December temperature patterns in Heidelberg, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Heidelberg, December typically has an average temperature of 11°C (53°F), with highs reaching up to 27°C (81°F) and lows dropping to around -4°C (25°F).
JanFebMarAprMayJunJulAugSepOctNovDec495561657479818178705652
Data source: Temperature data for Heidelberg 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 Heidelberg

In Heidelberg in December, the total precipitation amount is 133 mm (5.3 in) over the course of 12 days.

December Precipitation Trends in Heidelberg

The chart displays monthly precipitation patterns in Heidelberg, 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 Heidelberg, December typically receives around 133 mm (5.3 inches) of precipitation spread over approximately 12 days.
JanFebMarAprMayJunJulAugSepOctNovDec110140121127137168137132979972133
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Heidelberg

In Heidelberg in December, humidity is 87%. With an average temperature of 11°C (53°F), this humidity feels like a damp chill that clings to your skin, making it uncomfortable for traveling as it combines the cool air with a sense of heaviness, leaving you yearning for warmth and dryness.

December Average Humidity in Heidelberg

This chart illustrates the average monthly humidity levels in Heidelberg, 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 Heidelberg 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 Heidelberg

In Heidelberg 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 Heidelberg for better planning.

Maximum UV Index Levels in Heidelberg for December

The chart shows the monthly maximum UV Index (UVI) for Heidelberg 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 Heidelberg typically reaches 4, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec478111111111110864
Data source: Heidelberg 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 Heidelberg Compares to Other Months

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

This table compares monthly weather conditions in Heidelberg, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather10°C (50°F)110 mm (4.3 inches)82%moderate
February Weather13°C (55°F)140 mm (5.5 inches)80%high
March Weather16°C (61°F)121 mm (4.7 inches)80%very high
April Weather18°C (65°F)127 mm (5.0 inches)78%extreme
May Weather23°C (74°F)137 mm (5.4 inches)73%extreme
June Weather26°C (79°F)168 mm (6.6 inches)71%extreme
July Weather27°C (81°F)137 mm (5.4 inches)79%extreme
August Weather27°C (81°F)132 mm (5.2 inches)78%extreme
September Weather26°C (78°F)97 mm (3.8 inches)80%very high
October Weather21°C (70°F)99 mm (3.9 inches)76%very high
November Weather13°C (56°F)72 mm (2.8 inches)83%high
December Weather11°C (53°F)133 mm (5.3 inches)87%moderate

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