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December Weather in South Yarmouth, United States

Last updated: June 24, 2025

In South Yarmouth, United States, the average temperature in December hovers around 4°C (40°F), with a minimum dipping to -12°C (11°F) and a maximum reaching 15°C (60°F). Be prepared for 136 mm (5.4 in) of precipitation spread over 12 days, contributing to an average humidity of 80%.

December Temperature in South Yarmouth

In December in South Yarmouth, the average temperature is 4°C (40°F). Maximums can reach 15°C (60°F), and minimums can drop as low as -12°C (11°F). Travelers should be prepared for chilly conditions, with the possibility of warmer days interspersed among colder spells.

December Weather in South Yarmouth: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in South Yarmouth, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In South Yarmouth, December typically has an average temperature of 4°C (40°F), with highs reaching up to 15°C (60°F) and lows dropping to around -12°C (11°F).
JanFebMarAprMayJunJulAugSepOctNovDec353638455363707266594839
Data source: Temperature data for South Yarmouth 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 South Yarmouth

In South Yarmouth in December, the total precipitation amount reaches 136 mm (5.4 in) over the course of 12 days.

December Precipitation Trends in South Yarmouth

The chart displays monthly precipitation patterns in South Yarmouth, 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 South Yarmouth, December typically receives around 136 mm (5.4 inches) of precipitation spread over approximately 12 days.
JanFebMarAprMayJunJulAugSepOctNovDec94123118137119918382118175102136
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in South Yarmouth

In South Yarmouth in December, humidity is 80%. With an average temperature of 4°C (40°F), this humidity feels like a damp chill that seeps into your bones, making travel uncomfortable and requiring careful planning for warmth and moisture management.

December Average Humidity in South Yarmouth

This chart illustrates the average monthly humidity levels in South Yarmouth, 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 South Yarmouth is approximately 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec84%84%82%79%75%78%76%76%76%75%80%80%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in South Yarmouth

In South Yarmouth 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 South Yarmouth, you can visit Hourly UV Index in South Yarmouth.

Maximum UV Index Levels in South Yarmouth for December

The chart shows the monthly maximum UV Index (UVI) for South Yarmouth 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 South Yarmouth typically reaches 2, which falls under the low exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3468910998642
Data source: South Yarmouth 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 South Yarmouth Compares to Other Months

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

This table compares monthly weather conditions in South Yarmouth, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather2°C (36°F)94 mm (3.7 inches)84%moderate
February Weather2°C (36°F)123 mm (4.8 inches)84%moderate
March Weather3°C (38°F)118 mm (4.7 inches)82%high
April Weather7°C (46°F)137 mm (5.4 inches)79%very high
May Weather12°C (53°F)119 mm (4.7 inches)75%very high
June Weather17°C (63°F)91 mm (3.6 inches)78%very high
July Weather21°C (71°F)83 mm (3.3 inches)76%very high
August Weather22°C (72°F)82 mm (3.2 inches)76%very high
September Weather19°C (67°F)118 mm (4.7 inches)75%very high
October Weather15°C (59°F)175 mm (6.9 inches)75%high
November Weather9°C (48°F)102 mm (4.0 inches)80%moderate
December Weather4°C (40°F)136 mm (5.4 inches)80%low

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