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December Weather in Cos Cob, United States

Last updated: June 24, 2025

In December, the average temperature in Cos Cob, United States hovers around 3°C (39°F). While you might experience a chill with minimums dipping to -11°C (12°F), warmer days can reach a pleasant 17°C (62°F). Expect about 113 mm (4.5 in) of precipitation spread over 11 days, with an average humidity level of 80% contributing to a brisk atmosphere.

December Temperature in Cos Cob

In December in Cos Cob, the average temperature is 3°C (39°F). Maximums can reach 17°C (62°F), while minimums can drop as low as -11°C (12°F). Travelers should be prepared for a range of temperatures, from chilly to mild, and pack accordingly.

December Weather in Cos Cob: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in Cos Cob, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Cos Cob, December typically has an average temperature of 3°C (39°F), with highs reaching up to 17°C (62°F) and lows dropping to around -11°C (12°F).
JanFebMarAprMayJunJulAugSepOctNovDec333540506070777569604638
Data source: Temperature data for Cos Cob 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 Cos Cob

In Cos Cob in December, the total precipitation amount is 113 mm (4.5 in), spread over a period of 11 days.

December Precipitation Trends in Cos Cob

The chart displays monthly precipitation patterns in Cos Cob, 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 Cos Cob, December typically receives around 113 mm (4.5 inches) of precipitation spread over approximately 11 days.
JanFebMarAprMayJunJulAugSepOctNovDec6910193116112941391189313190114
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Cos Cob

In Cos Cob in December, humidity is 80%. With an average temperature of 3°C (39°F), this humidity feels like you are wrapped in a damp, chilly blanket, making it quite uncomfortable for traveling.

December Average Humidity in Cos Cob

This chart illustrates the average monthly humidity levels in Cos Cob, 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 Cos Cob is approximately 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec84%82%81%78%70%69%62%65%68%74%82%80%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Cos Cob

In Cos Cob 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 Cos Cob, you can visit Hourly UV Index in Cos Cob.

Maximum UV Index Levels in Cos Cob for December

The chart shows the monthly maximum UV Index (UVI) for Cos Cob 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 Cos Cob typically reaches 2, which falls under the low exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec35681010998642
Data source: Cos Cob 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 Cos Cob Compares to Other Months

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

This table compares monthly weather conditions in Cos Cob, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather1°C (34°F)69 mm (2.7 inches)84%moderate
February Weather2°C (36°F)101 mm (4.0 inches)82%moderate
March Weather5°C (41°F)93 mm (3.7 inches)81%high
April Weather10°C (50°F)116 mm (4.6 inches)78%very high
May Weather15°C (60°F)112 mm (4.4 inches)69%very high
June Weather21°C (70°F)93 mm (3.7 inches)69%very high
July Weather25°C (77°F)139 mm (5.5 inches)62%very high
August Weather24°C (75°F)118 mm (4.6 inches)65%very high
September Weather21°C (69°F)93 mm (3.6 inches)68%very high
October Weather15°C (60°F)131 mm (5.2 inches)74%high
November Weather8°C (47°F)90 mm (3.6 inches)82%moderate
December Weather3°C (39°F)113 mm (4.5 inches)80%low

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