Portland
Oregon, USA
Long-term weather forecast
Long-term weather forecast

May weather forecast and climate
Portland, OR

A colorful autumn view of the outline of Portland City, Oregon, with mountains in the distance
A colorful autumn view of the outline of Portland City, Oregon, with mountains in the distance
The average temperatures in May in Portland are between 48.9°F (9.4°C) to 68°F (20°C) as the skies are clear for long periods. May is warm and sunny, with 276 hours of brilliant sunshine in the historic city.
Freshwater flows through the rivers and creeks, which starts the fishing season in Portland. The rainfall is moderate to the tune of 2.5" (63.5mm) with intermittent showers, mainly in the morning and afternoon. Explore the west hills area to experience the blossoming flowers and the sweet air of the spring season.
A warm jacket is usually enough for the temperate conditions in May.

What is the temperature in May in Portland?

In Portland, in May, the average high-temperature is 68°F (20°C), and the average low-temperature is 48.6°F (9.2°C).

What is the average humidity in May in Portland?

In May, the average relative humidity in Portland, Oregon, is 68.7%.

How many days does it rain in May in Portland?

In May, in Portland, the rain falls for 13.6 days. Throughout May, 2.5" (62.7mm) of precipitation is accumulated.

What is the average length of the day in May in Portland?

The average length of the day in May in Portland is 14.9h.

How many hours of sunshine does Portland have in May?

In May, the average sunshine in Portland, Oregon, is 8.9h.

What is the UV index reading in May in Portland?

In Portland, Oregon, the average daily maximum UV index in May is 6. A UV Index reading of 6 to 7 represents a high health risk from unsafe exposure to the Sun's UV rays.
Average temperature in May - Portland, OR
  • Average high temperature in May: 68°F

The warmest month (with the highest average high temperature) is August (81.1°F).
The month with the lowest average high temperature is December (45.6°F).

  • Average low temperature in May: 48.6°F

The month with the highest average low temperature is August (58°F).
The coldest month (with the lowest average low temperature) is December (35.2°F).

Average humidity in May - Portland, OR
  • Average humidity in May: 68.7%

The month with the highest relative humidity is December (82.7%).
The month with the lowest relative humidity is July (62.8%).

Average rainfall in May - Portland, OR
  • Average rainfall in May: 2.5"

The wettest month (with the highest rainfall) is November (5.6").
Driest months (with the lowest rainfall) are July and August (0.7").

Average rainfall days in May - Portland, OR
  • Average rainfall days in May: 13.6 days

The month with the highest number of rainy days is November (19 days).
The month with the lowest number of rainy days is August (3.9 days).

Average snowfall in May - Portland, OR
  • Average snowfall in May: 0"

The month with the highest snowfall is February (2.1").
Months with the lowest snowfall are April, May, June, July, August, September and October (0").

Average snowfall days in May - Portland, OR
  • Average snowfall days in May: 0 days

Months with the highest number of snowfall days are February and December (1.5 days).
Months with the lowest number of snowfall days are April, May, June, July, August, September and October (0 days).

Average daylight in May / Average sunshine in May - Portland, OR
  • Average daylight in May: 14.9h

The month with the longest days is June (Average daylight: 15.6h).
The month with shortest days is December (Average daylight: 8.8h).

  • Average sunshine in May: 8.9h

The month with most sunshine is July (Average sunshine: 10.7h).
The month with least sunshine is December (Average sunshine: 2.1h).

Average UV index in May - Portland, OR
  • Average UV index in May: 6

The month with the highest UV index is July (UV index 8).
Months with the lowest UV index are January and December (UV index 1).