December Weather in Groton, United States

Last updated: June 24, 2025

In December, the average temperature in Groton, United States hovers around -5°C (23°F). Expect chilly extremes, with minimums plunging to -28°C (-18°F) and highs peaking at 14°C (58°F). The region experiences 33 mm (1.3 in) of precipitation over approximately 5 days, contributing to a notable average humidity of 81%.

December Temperature in Groton

In December in Groton, the average temperature is -5°C (23°F). Maximum temperatures can reach 14°C (58°F), while minimums can drop as low as -28°C (-18°F). Be prepared for a significant temperature range when traveling to Groton during this time.

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

The chart illustrates December temperature patterns in Groton, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Groton, December typically has an average temperature of -5°C (23°F), with highs reaching up to 14°C (58°F) and lows dropping to around -28°C (-18°F).

Data source: Temperature data for Groton generated using information from the Copernicus Climate Change Service.

December Precipitation in Groton

In Groton in December, the precipitation amount is 33 mm (1.3 in) over the course of 5 days.

December Precipitation Trends in Groton

The chart displays monthly precipitation patterns in Groton, 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 Groton, December typically receives around 33 mm (1.3 inches) of precipitation spread over approximately 5 days.

Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

December Humidity in Groton

In Groton in December, humidity is 81%. With an average temperature of -5°C (23°F), this humidity feels like a biting chill that penetrates deep into your bones, making outdoor activities uncomfortable and travel a challenge.

December Average Humidity in Groton

This chart illustrates the average monthly humidity levels in Groton, 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 Groton is approximately 81%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Groton

In Groton in December, the maximum UV index is 2, which corresponds to a low exposure category. With this level of UV radiation, the time to burn is approximately 45 minutes. To learn more about the hourly UV index in Groton, you can visit Hourly UV Index in Groton.

Maximum UV Index Levels in Groton for December

The chart shows the monthly maximum UV Index (UVI) for Groton 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 Groton typically reaches 2, which falls under the low exposure category.

Data source: Groton 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 Groton Compares to Other Months

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

This table compares monthly weather conditions in Groton, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	-10°C (15°F)	18 mm (0.7 inches)	81%	moderate
February Weather	-10°C (14°F)	16 mm (0.6 inches)	85%	moderate
March Weather	-1°C (31°F)	35 mm (1.4 inches)	76%	moderate
April Weather	5°C (41°F)	47 mm (1.9 inches)	79%	high
May Weather	14°C (57°F)	64 mm (2.5 inches)	76%	very high
June Weather	22°C (71°F)	65 mm (2.6 inches)	81%	very high
July Weather	24°C (75°F)	76 mm (3.0 inches)	82%	very high
August Weather	21°C (71°F)	108 mm (4.2 inches)	82%	very high
September Weather	17°C (63°F)	88 mm (3.5 inches)	77%	high
October Weather	8°C (46°F)	76 mm (3.0 inches)	76%	moderate
November Weather	0°C (33°F)	17 mm (0.7 inches)	84%	moderate
December Weather	-5°C (23°F)	33 mm (1.3 inches)	81%	low