January Weather in Portland, United States

Last updated: June 24, 2025

In January, the average temperature in Portland, United States hovers around 4°C (40°F), with a chill that can dip as low as -15°C (5°F) and occasionally rise to a comfortable 22°C (73°F). This month sees an average precipitation of 105 mm (4.1 in) spread over 11 days, contributing to a high average humidity of 87%. Prepare for a mix of weather as you navigate this chilly yet damp month!

January Temperature in Portland

In January in Portland, the average temperature is 4°C (40°F), with maximums reaching up to 22°C (73°F) and minimums dropping as low as -15°C (5°F). This means travelers should be prepared for a wide range of weather conditions during their visit.

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

The chart illustrates January temperature patterns in Portland, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Portland, January typically has an average temperature of 4°C (40°F), with highs reaching up to 22°C (73°F) and lows dropping to around -15°C (5°F).

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

January Precipitation in Portland

In Portland in January, the precipitation amount is 105 mm (4.1 in) over the course of 11 days.

January Precipitation Trends in Portland

The chart displays monthly precipitation patterns in Portland, 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 Portland, January typically receives around 105 mm (4.1 inches) of precipitation spread over approximately 11 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 Portland

In Portland in January humidity is 87%. With an average temperature of 4°C (40°F), this humidity feels like an uncomfortable chill that seeps into your bones, making it essential to dress warmly and prepare for damp conditions, which can dampen your spirits while traveling.

January Average Humidity in Portland

This chart illustrates the average monthly humidity levels in Portland, 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 Portland is approximately 87%, 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 Portland

In Portland 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 Portland, you can check the information here.

Maximum UV Index Levels in Portland for January

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

Data source: Portland 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 Portland Compares to Other Months

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

This table compares monthly weather conditions in Portland, showing how January’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	4°C (40°F)	105 mm (4.1 inches)	87%	moderate
February Weather	7°C (44°F)	185 mm (7.3 inches)	86%	high
March Weather	11°C (52°F)	157 mm (6.2 inches)	86%	high
April Weather	15°C (59°F)	150 mm (5.9 inches)	82%	very high
May Weather	21°C (70°F)	122 mm (4.8 inches)	82%	very high
June Weather	25°C (77°F)	141 mm (5.5 inches)	83%	extreme
July Weather	27°C (80°F)	125 mm (4.9 inches)	80%	extreme
August Weather	25°C (78°F)	124 mm (4.9 inches)	74%	very high
September Weather	23°C (74°F)	125 mm (4.9 inches)	71%	very high
October Weather	17°C (63°F)	138 mm (5.4 inches)	78%	high
November Weather	9°C (48°F)	88 mm (3.4 inches)	88%	moderate
December Weather	7°C (45°F)	147 mm (5.8 inches)	88%	moderate