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December Weather in Sumner, United States

Last updated: June 24, 2025

In December, the average temperature in Sumner, United States hovers around 4°C (39°F), with a chilly minimum of -17°C (1°F) and a pleasant maximum reaching 20°C (69°F). Expect 95 mm (3.7 in) of precipitation spread over 9 days, and embrace the high average humidity of 87% that characterizes this crisp season.

December Temperature in Sumner

In December in Sumner, the average temperature is 4°C (39°F), with maximums reaching 20°C (69°F) and minimums dropping as low as -17°C (1°F). Be prepared for a wide range of temperatures when traveling during this time.

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

The chart illustrates December temperature patterns in Sumner, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Sumner, December typically has an average temperature of 4°C (39°F), with highs reaching up to 20°C (69°F) and lows dropping to around -17°C (1°F).
JanFebMarAprMayJunJulAugSepOctNovDec333646556877797672604439
Data source: Temperature data for Sumner 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 Sumner

In Sumner in December, the precipitation amount is 95 mm (3.7 in) over the course of 9 days.

December Precipitation Trends in Sumner

The chart displays monthly precipitation patterns in Sumner, 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 Sumner, December typically receives around 95 mm (3.7 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec9110713312013311297927010010295
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Sumner

In Sumner in December, humidity is 87%. With an average temperature of 4°C (39°F), this humidity feels like a damp chill that seeps into your bones, making travel uncomfortable and gritty, as the air hangs heavy and clings to your skin.

December Average Humidity in Sumner

This chart illustrates the average monthly humidity levels in Sumner, 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 Sumner is approximately 87%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec84%82%84%83%80%83%82%83%79%79%88%87%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Sumner

In Sumner in December, the maximum UV index is 3, which corresponds to a moderate Exposure Category. The time to burn is approximately 30 minutes. For more details on the hourly UV index in Sumner, you can check the information here.

Maximum UV Index Levels in Sumner for December

The chart shows the monthly maximum UV Index (UVI) for Sumner 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 Sumner typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec357910111099643
Data source: Sumner 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 Sumner Compares to Other Months

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

This table compares monthly weather conditions in Sumner, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather1°C (33°F)91 mm (3.6 inches)84%moderate
February Weather2°C (37°F)107 mm (4.2 inches)82%moderate
March Weather8°C (47°F)133 mm (5.2 inches)84%high
April Weather13°C (56°F)120 mm (4.7 inches)83%very high
May Weather20°C (68°F)133 mm (5.3 inches)80%very high
June Weather25°C (77°F)112 mm (4.4 inches)83%extreme
July Weather26°C (80°F)97 mm (3.8 inches)82%very high
August Weather25°C (77°F)92 mm (3.6 inches)82%very high
September Weather22°C (73°F)70 mm (2.7 inches)79%very high
October Weather16°C (60°F)100 mm (3.9 inches)79%high
November Weather7°C (44°F)102 mm (4.0 inches)88%moderate
December Weather4°C (39°F)95 mm (3.7 inches)87%moderate

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