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December Weather in Hillsboro, United States

Last updated: June 24, 2025

In December, the average temperature in Hillsboro, United States hovers around 3°C (38°F). Temperatures can vary widely, with minimums plunging to -15°C (6°F) and maximums reaching 23°C (74°F). Expect about 29 mm (1.1 in) of precipitation spread over 3 days, along with an average humidity of 84%.

December Temperature in Hillsboro

In December in Hillsboro, the average temperature is 3°C (38°F), with maximums reaching up to 23°C (74°F) and minimums dropping as low as -15°C (6°F). Travelers should be prepared for a wide range of temperatures, ensuring they pack both warm clothing for the cold nights and lighter layers for the milder days.

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

The chart illustrates December temperature patterns in Hillsboro, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Hillsboro, December typically has an average temperature of 3°C (38°F), with highs reaching up to 23°C (74°F) and lows dropping to around -15°C (6°F).
JanFebMarAprMayJunJulAugSepOctNovDec333347556577807772574538
Data source: Temperature data for Hillsboro 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 Hillsboro

In Hillsboro in December, the precipitation amount is 29 mm (1.1 in) over the course of 3 days.

December Precipitation Trends in Hillsboro

The chart displays monthly precipitation patterns in Hillsboro, 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 Hillsboro, December typically receives around 29 mm (1.1 inches) of precipitation spread over approximately 3 days.
JanFebMarAprMayJunJulAugSepOctNovDec32338073175967913880972929
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Hillsboro

In Hillsboro in December, humidity is 84%. With an average temperature of 3°C (38°F), this humidity feels like a damp chill that seeps into your bones, making traveling uncomfortable as the cold air clings to you and the moisture creates an oppressive heaviness in the atmosphere.

December Average Humidity in Hillsboro

This chart illustrates the average monthly humidity levels in Hillsboro, 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 Hillsboro is approximately 84%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec76%78%70%73%82%82%81%78%71%71%81%84%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Hillsboro

In Hillsboro 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 Hillsboro, you can check the information here.

Maximum UV Index Levels in Hillsboro for December

The chart shows the monthly maximum UV Index (UVI) for Hillsboro 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 Hillsboro typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3679101111109743
Data source: Hillsboro 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 Hillsboro Compares to Other Months

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

This table compares monthly weather conditions in Hillsboro, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather0°C (33°F)32 mm (1.3 inches)76%moderate
February Weather1°C (34°F)33 mm (1.3 inches)77%high
March Weather8°C (47°F)80 mm (3.1 inches)70%high
April Weather13°C (55°F)73 mm (2.9 inches)73%very high
May Weather19°C (66°F)175 mm (6.9 inches)82%very high
June Weather25°C (78°F)95 mm (3.8 inches)82%extreme
July Weather27°C (80°F)79 mm (3.1 inches)81%extreme
August Weather25°C (77°F)138 mm (5.4 inches)78%very high
September Weather22°C (72°F)80 mm (3.1 inches)71%very high
October Weather14°C (57°F)97 mm (3.8 inches)71%high
November Weather7°C (45°F)29 mm (1.1 inches)81%moderate
December Weather3°C (38°F)29 mm (1.1 inches)84%moderate

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