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December Weather in Waterloo, United States

Last updated: June 24, 2025

In December, the average temperature in Waterloo, United States hovers around 4°C (40°F), with fluctuations ranging from a chilly -15°C (4°F) to a warm 24°C (76°F). Expect about 68 mm (2.7 in) of precipitation spread over 7 days, contributing to the 86% average humidity that characterizes this month.

December Temperature in Waterloo

In December in Waterloo, the average temperature is 4°C (40°F). Maximum temperatures can reach 24°C (76°F), while minimums can drop as low as -15°C (4°F). Travelers should be prepared for a wide range of temperatures and pack accordingly.

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

The chart illustrates December temperature patterns in Waterloo, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Waterloo, December typically has an average temperature of 4°C (40°F), with highs reaching up to 24°C (76°F) and lows dropping to around -15°C (4°F).
JanFebMarAprMayJunJulAugSepOctNovDec343748566777807772594540
Data source: Temperature data for Waterloo 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 Waterloo

In Waterloo in December, the precipitation amount is 68 mm (2.7 in) over the course of 7 days.

December Precipitation Trends in Waterloo

The chart displays monthly precipitation patterns in Waterloo, 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 Waterloo, December typically receives around 68 mm (2.7 inches) of precipitation spread over approximately 7 days.
JanFebMarAprMayJunJulAugSepOctNovDec79871361421498789123661097568
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Waterloo

In Waterloo in December humidity is 86%. With an average temperature of 4°C (40°F), this humidity feels like a damp chill that seeps into your bones, making outdoor activities uncomfortable and travel cumbersome as you navigate through a thick, heavy air that clings to your skin.

December Average Humidity in Waterloo

This chart illustrates the average monthly humidity levels in Waterloo, 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 Waterloo is approximately 86%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec82%80%80%80%82%83%81%80%76%76%85%86%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Waterloo

In Waterloo 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 Waterloo, you can check the information here.

Maximum UV Index Levels in Waterloo for December

The chart shows the monthly maximum UV Index (UVI) for Waterloo 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 Waterloo typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3579101110109753
Data source: Waterloo 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 Waterloo Compares to Other Months

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

This table compares monthly weather conditions in Waterloo, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather1°C (34°F)79 mm (3.1 inches)82%moderate
February Weather3°C (37°F)87 mm (3.4 inches)80%moderate
March Weather9°C (48°F)136 mm (5.4 inches)80%high
April Weather13°C (56°F)142 mm (5.6 inches)80%very high
May Weather20°C (68°F)149 mm (5.9 inches)82%very high
June Weather25°C (77°F)87 mm (3.4 inches)83%extreme
July Weather27°C (80°F)89 mm (3.5 inches)81%very high
August Weather25°C (77°F)123 mm (4.8 inches)80%very high
September Weather22°C (73°F)66 mm (2.6 inches)76%very high
October Weather15°C (60°F)109 mm (4.3 inches)76%high
November Weather7°C (45°F)75 mm (2.9 inches)85%moderate
December Weather4°C (40°F)68 mm (2.7 inches)86%moderate

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