May Weather in Portland, Australia

Last updated: August 22, 2025

In Portland, Australia, the average temperature in May hovers around 9°C (49°F). You can expect a minimum dip to -3°C (27°F) and a pleasant maximum of 21°C (71°F). During this time, precipitation can reach 26 mm (1.0 in) over about 5 days, with an average humidity level of 78%.

May Temperature in Portland

In May in Portland, the average temperature is 9°C (49°F), with a maximum reaching 21°C (71°F) and a minimum dropping as low as -3°C (27°F). Be prepared for a range of temperatures during your travels, so pack accordingly!

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

The chart illustrates May 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, May typically has an average temperature of 9°C (49°F), with highs reaching up to 21°C (71°F) and lows dropping to around -3°C (27°F).

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

May Precipitation in Portland

In Portland in May, the precipitation amount is 26 mm (1.0 in) over the course of 5 days.

May Precipitation Trends in Portland

The chart displays monthly precipitation patterns in Portland, with values for each month alongside May’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how May’s conditions compare to those of other months. In Portland, May typically receives around 26 mm (1.0 inches) of precipitation spread over approximately 5 days.

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

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

May Humidity in Portland

In Portland in May, humidity is 78%. With an average temperature of 9°C (49°F), this humidity feels like a damp chill that clings to your skin, making it essential to dress in layers while traveling, as the cool air combines with the moisture to create a brisk and invigorating atmosphere.

May Average Humidity in Portland

This chart illustrates the average monthly humidity levels in Portland, with May’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In May, average humidity in Portland is approximately 78%, offering insight into how humid the weather typically is during this month.

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

May UV Index in Portland

In Portland in May, the maximum UV index is 6, which corresponds to a high Exposure Category. The time to burn is approximately 25 minutes. To find the hourly UV index in Portland, you can refer to this Hourly UV Index in Portland.

Maximum UV Index Levels in Portland for May

The chart shows the monthly maximum UV Index (UVI) for Portland in May, 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 May, the maximum UV index in Portland typically reaches 6, which falls under the high exposure category.

Data source: Portland May 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 May 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 May’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 May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	21°C (70°F)	44 mm (1.7 inches)	55%	extreme
February Weather	19°C (66°F)	72 mm (2.8 inches)	60%	extreme
March Weather	17°C (63°F)	113 mm (4.4 inches)	68%	extreme
April Weather	13°C (56°F)	23 mm (0.9 inches)	74%	very high
May Weather	9°C (49°F)	26 mm (1.0 inches)	78%	high
June Weather	7°C (44°F)	28 mm (1.1 inches)	78%	moderate
July Weather	6°C (43°F)	33 mm (1.3 inches)	79%	moderate
August Weather	6°C (44°F)	46 mm (1.8 inches)	74%	high
September Weather	10°C (50°F)	35 mm (1.4 inches)	69%	very high
October Weather	14°C (57°F)	57 mm (2.3 inches)	57%	extreme
November Weather	16°C (61°F)	88 mm (3.5 inches)	53%	extreme
December Weather	19°C (66°F)	76 mm (3.0 inches)	62%	extreme