December Weather in Johnston, United States

Last updated: June 24, 2025

In Johnston, United States, the average temperature in December hovers around 10°C (51°F). Temperatures can swing from a brisk -6°C (21°F) to a warm 28°C (82°F). During this time, expect about 119 mm (4.7 in) of precipitation spread over 9 days, contributing to an average humidity level of 87%. Prepare for a mix of cool and damp days!

December Temperature in Johnston

In December in Johnston, the average temperature is 10°C (51°F). The maximum can reach 28°C (82°F), while the minimum can be as low as -6°C (21°F). Travelers should be prepared for a wide range of temperatures and pack accordingly.

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

The chart illustrates December temperature patterns in Johnston, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Johnston, December typically has an average temperature of 10°C (51°F), with highs reaching up to 28°C (82°F) and lows dropping to around -6°C (21°F).

Data source: Temperature data for Johnston generated using information from the Copernicus Climate Change Service.

December Precipitation in Johnston

In Johnston in December, the precipitation amount is 119 mm (4.7 in) occurring over a span of 9 days.

December Precipitation Trends in Johnston

The chart displays monthly precipitation patterns in Johnston, 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 Johnston, December typically receives around 119 mm (4.7 inches) of precipitation spread over approximately 9 days.

Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

December Humidity in Johnston

In Johnston in December humidity is 87%. With an average temperature of 10°C (51°F), this humidity feels like a heavy blanket enveloping you, making outdoor activities uncomfortable and sticky, and often requiring frequent breaks to stay hydrated and cool.

December Average Humidity in Johnston

This chart illustrates the average monthly humidity levels in Johnston, 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 Johnston is approximately 87%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Johnston

In Johnston in December, the maximum UV index reaches 4, which corresponds to a moderate Exposure Category. With a time to burn of 30 minutes, it’s important to take precautions to protect your skin. You can find more details in the Hourly UV Index in Johnston for better planning.

Maximum UV Index Levels in Johnston for December

The chart shows the monthly maximum UV Index (UVI) for Johnston 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 Johnston typically reaches 4, which falls under the moderate exposure category.

Data source: Johnston 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 Johnston Compares to Other Months

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

This table compares monthly weather conditions in Johnston, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	9°C (48°F)	84 mm (3.3 inches)	86%	moderate
February Weather	12°C (54°F)	114 mm (4.5 inches)	81%	high
March Weather	14°C (58°F)	85 mm (3.4 inches)	81%	very high
April Weather	18°C (65°F)	115 mm (4.5 inches)	79%	very high
May Weather	23°C (74°F)	110 mm (4.3 inches)	75%	extreme
June Weather	26°C (79°F)	101 mm (4.0 inches)	75%	extreme
July Weather	28°C (82°F)	137 mm (5.4 inches)	80%	extreme
August Weather	27°C (80°F)	142 mm (5.6 inches)	81%	extreme
September Weather	25°C (77°F)	84 mm (3.3 inches)	83%	very high
October Weather	20°C (69°F)	80 mm (3.1 inches)	78%	very high
November Weather	13°C (55°F)	69 mm (2.7 inches)	85%	high
December Weather	10°C (51°F)	119 mm (4.7 inches)	87%	moderate