January Weather in Greenwich, United States

Last updated: June 24, 2025

In Greenwich, United States, the average temperature in January hovers around -2°C (29°F), with extremes ranging from a frigid -23°C (-9°F) to a milder 20°C (68°F). During this month, expect approximately 78 mm (3.1 in) of precipitation over about 10 days, contributing to an average humidity of 88%. Prepare accordingly for the chilly and damp conditions!

January Temperature in Greenwich

In January in Greenwich, the average temperature is -2°C (29°F). Maximum temperatures can reach 20°C (68°F), while minimums can drop as low as -23°C (-9°F). Travelers should be prepared for a wide range of temperatures and pack accordingly to enjoy their stay in Greenwich.

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

The chart illustrates January temperature patterns in Greenwich, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Greenwich, January typically has an average temperature of -2°C (29°F), with highs reaching up to 20°C (68°F) and lows dropping to around -23°C (-9°F).

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

January Precipitation in Greenwich

In Greenwich in January, the precipitation amount is 78 mm (3.1 in) over the course of 10 days.

January Precipitation Trends in Greenwich

The chart displays monthly precipitation patterns in Greenwich, 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 Greenwich, January typically receives around 78 mm (3.1 inches) of precipitation spread over approximately 10 days.

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

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

January Humidity in Greenwich

In Greenwich in January, humidity is 88%. With an average temperature of -2°C (29°F), this humidity feels like a biting chill in the air that penetrates layers of clothing, making outdoor activities challenging and potentially uncomfortable for travelers.

January Average Humidity in Greenwich

This chart illustrates the average monthly humidity levels in Greenwich, 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 Greenwich is approximately 88%, 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 Greenwich

In Greenwich 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 Greenwich, you can check the information here.

Maximum UV Index Levels in Greenwich for January

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

Data source: Greenwich 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 Greenwich Compares to Other Months

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

This table compares monthly weather conditions in Greenwich, 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)	78 mm (3.1 inches)	88%	moderate
February Weather	0°C (32°F)	92 mm (3.6 inches)	87%	moderate
March Weather	4°C (40°F)	97 mm (3.8 inches)	87%	high
April Weather	10°C (50°F)	123 mm (4.8 inches)	87%	very high
May Weather	16°C (62°F)	129 mm (5.1 inches)	81%	very high
June Weather	21°C (71°F)	136 mm (5.4 inches)	82%	very high
July Weather	24°C (75°F)	128 mm (5.0 inches)	81%	very high
August Weather	22°C (72°F)	91 mm (3.6 inches)	78%	very high
September Weather	20°C (67°F)	79 mm (3.1 inches)	78%	very high
October Weather	14°C (57°F)	96 mm (3.8 inches)	82%	high
November Weather	5°C (41°F)	88 mm (3.4 inches)	89%	moderate
December Weather	1°C (35°F)	84 mm (3.3 inches)	86%	low