January Weather in Decatur, United States

Last updated: June 24, 2025

In January, the average temperature in Decatur, United States hovers around -2°C (29°F), with potential extremes ranging from a chilling -25°C (-13°F) to a mild 18°C (64°F). This period also sees about 74 mm (2.9 in) of precipitation spread over 8 days, contributing to the average humidity of a brisk 85%.

January Temperature in Decatur

In January in Decatur, the average temperature is -2°C (29°F). The maximum can reach 18°C (64°F), while the minimum can drop as low as -25°C (-13°F). Be prepared for significant temperature fluctuations during your travels.

January Weather in Decatur: Daily Temperature Highs, Lows, and Averages

The chart illustrates January temperature patterns in Decatur, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Decatur, January typically has an average temperature of -2°C (29°F), with highs reaching up to 18°C (64°F) and lows dropping to around -25°C (-13°F).

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

January Precipitation in Decatur

In Decatur in January, the precipitation amount is 74 mm (2.9 in) over a period of 8 days.

January Precipitation Trends in Decatur

The chart displays monthly precipitation patterns in Decatur, with values for each month alongside January’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how January’s conditions compare to those of other months. In Decatur, January typically receives around 74 mm (2.9 inches) of precipitation spread over approximately 8 days.

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

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Millimeters (mm) Inches (in)

January Humidity in Decatur

In Decatur in January, humidity is 85%. With an average temperature of -2°C (29°F), this humidity feels like a chilling, damp blanket that clings to your skin, making travel uncomfortable and often prompting an urgent search for warmth and shelter.

January Average Humidity in Decatur

This chart illustrates the average monthly humidity levels in Decatur, with January’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In January, average humidity in Decatur is approximately 85%, offering insight into how humid the weather typically is during this month.

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

January UV Index in Decatur

In Decatur in January, 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 Decatur, you can check the information here.

Maximum UV Index Levels in Decatur for January

The chart shows the monthly maximum UV Index (UVI) for Decatur in January, 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 January, the maximum UV index in Decatur typically reaches 3, which falls under the moderate exposure category.

Data source: Decatur January 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 January Weather in Decatur Compares to Other Months

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

This table compares monthly weather conditions in Decatur, showing how January’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	-2°C (29°F)	74 mm (2.9 inches)	85%	moderate
February Weather	0°C (32°F)	83 mm (3.3 inches)	85%	moderate
March Weather	5°C (41°F)	100 mm (4.0 inches)	86%	high
April Weather	10°C (51°F)	91 mm (3.6 inches)	87%	very high
May Weather	17°C (63°F)	124 mm (4.9 inches)	81%	very high
June Weather	22°C (73°F)	114 mm (4.5 inches)	82%	very high
July Weather	25°C (76°F)	102 mm (4.0 inches)	81%	very high
August Weather	23°C (74°F)	99 mm (3.9 inches)	79%	very high
September Weather	20°C (69°F)	68 mm (2.7 inches)	78%	very high
October Weather	14°C (57°F)	98 mm (3.9 inches)	81%	high
November Weather	5°C (42°F)	82 mm (3.2 inches)	89%	moderate
December Weather	2°C (35°F)	64 mm (2.5 inches)	86%	low