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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 9°C (49°F), offering a refreshing climate. Temperatures can vary from a brisk -1°C (31°F) to a comfortable 23°C (74°F). With an expected precipitation total of 95 mm (3.7 in) over approximately 9 days, it's advisable to carry an umbrella. Additionally, the air tends to be quite humid, with an average humidity of 80%, making it essential to dress accordingly for comfort!

December Temperature in Waterloo

In December in Waterloo, the average temperature is 9°C (49°F). The maximum can reach 23°C (74°F), while the minimum can be as low as -1°C (31°F). Be prepared for a wide range of temperatures when traveling during this time.

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 9°C (49°F), with highs reaching up to 23°C (74°F) and lows dropping to around -1°C (31°F).
JanFebMarAprMayJunJulAugSepOctNovDec505256626874767572655549
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 95 mm (3.7 in) over the course of 9 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 95 mm (3.7 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec110958944202002314795
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 80%. With an average temperature of 9°C (49°F), this humidity feels like a damp chill that seeps into your bones, making outdoor activities less enjoyable and prompting a need for layered clothing to stay comfortable while traveling.

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 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec82%84%82%78%71%64%59%54%55%62%78%80%
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.
JanFebMarAprMayJunJulAugSepOctNovDec3588101111109643
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 Weather10°C (50°F)110 mm (4.3 inches)82%moderate
February Weather11°C (52°F)95 mm (3.7 inches)84%moderate
March Weather13°C (56°F)89 mm (3.5 inches)82%very high
April Weather17°C (62°F)44 mm (1.7 inches)78%very high
May Weather20°C (68°F)20 mm (0.8 inches)71%very high
June Weather24°C (75°F)2 mm (0.1 inches)64%extreme
July Weather24°C (76°F)0 mm (0.0 inches)58%extreme
August Weather24°C (76°F)0 mm (0.0 inches)54%very high
September Weather22°C (72°F)2 mm (0.1 inches)55%very high
October Weather18°C (65°F)30 mm (1.2 inches)62%high
November Weather13°C (55°F)47 mm (1.8 inches)78%moderate
December Weather9°C (49°F)95 mm (3.7 inches)80%moderate

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