May weather forecast and climate
Portland, OR

A colorful autumn view of the outline of Portland City, Oregon, USA
A colorful autumn view of the outline of Portland City, Oregon, USA

Weather in May

The last month of the spring, May, is a comfortable month in Portland, Oregon, with average temperature varying between 67.1°F (19.5°C) and 44.2°F (6.8°C).

Temperature

In Portland, the average high-temperature in May marginally rises, from a moderate 58.6°F (14.8°C) in April, to a comfortable 67.1°F (19.5°C). In May, the average low-temperature is 44.2°F (6.8°C).

Humidity

In Portland, Oregon, the average relative humidity in May is 72%.

Rainfall

In May, the rain falls for 13.8 days. Throughout May, 1.77" (45mm) of precipitation is accumulated. In Portland, during the entire year, the rain falls for 173.1 days and collects up to 31.18" (792mm) of precipitation.

Snowfall

April through October are months without snowfall.

Daylight

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

Sunshine

In May, the average sunshine in Portland is 8.7h.

UV index

In May, the average daily maximum UV index is 4. A UV Index value of 3 to 5 symbolizes a medium health hazard from unsafe exposure to the UV radiation for ordinary individuals.
Note: The daily maximum UV index of 4 in May interpret into the following advice:
Take precautions - Protection against sun damage is advised. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.
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FAQ

What is the temperature in May in Portland?

The average high-temperature, in May, in Portland, Oregon, is 67.1°F (19.5°C), while the average low-temperature is 44.2°F (6.8°C).

What is the average humidity in May in Portland?

The average relative humidity in May in Portland is 72%.

How many days does it rain in May in Portland?

In Portland, Oregon, in May, it is raining for 13.8 days, with typically 1.77" (45mm) of accumulated precipitation.

When it does not snow in Portland?

In Portland snow does not fall in April through October.

How many hours of daylight does Portland have in May?

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

How many hours of sunshine does Portland have in May?

The average sunshine in May in Portland is 8.7h.

What is the UV index reading in May in Portland?

The average daily maximum UV index in May in Portland is 4. A UV Index reading of 3 to 5 represents a moderate vulnerability from the exposure to the Sun's UV rays.

Average temperature in May
Portland, OR

Average temperature in May - Portland, OR
  • Average high temperature in May: 67.1°F

The warmest month (with the highest average high temperature) is August (81.5°F).
The month with the lowest average high temperature is December (44.1°F).

  • Average low temperature in May: 44.2°F

The month with the highest average low temperature is August (55°F).
The coldest month (with the lowest average low temperature) is December (34.7°F).

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Average pressure in May
Portland, OR

Average pressure in May - Portland, OR
  • Average pressure in May: 30.03"

The month with the highest atmospheric pressure is January (30.12").
The month with the lowest atmospheric pressure is August (30").

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Average wind speed in May
Portland, OR

Average wind speed in May - Portland, OR
  • Average wind speed in May: 4.2mph

The windiest month (with the highest average wind speed) is January (5.8mph).
The calmest month (with the lowest average wind speed) is August (3.9mph).

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Average humidity in May
Portland, OR

Average humidity in May - Portland, OR
  • Average humidity in May: 72%

Months with the highest relative humidity are January, February and December (83%).
The month with the lowest relative humidity is August (63%).

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Average rainfall in May
Portland, OR

Average rainfall in May - Portland, OR
  • Average rainfall in May: 1.77"

The wettest month (with the highest rainfall) is December (4.53").
The driest month (with the least rainfall) is July (0.31").

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Average rainfall days in May
Portland, OR

Average rainfall days in May - Portland, OR
  • Average rainfall days in May: 13.8 days

The month with the highest number of rainy days is March (20.4 days).
The month with the least rainy days is July (4.9 days).

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Average snowfall in May
Portland, OR

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

The month with the highest snowfall is March (1.5").
Months with the least snowfall are April, May, June, July, August, September and October (0").

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Average snowfall days in May
Portland, OR

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

The month with the highest number of snowfall days is February (2.3 days).
Months with the least snowfall days are May, June, July, August, September and October (0 days).

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Average daylight in May /
Average sunshine in May
Portland, OR

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 the shortest days is December (Average daylight: 8.8h).

  • Average sunshine in May: 8.7h

The month with the most sunshine is August (Average sunshine: 10.9h).
The month with the least sunshine is January (Average sunshine: 4.1h).

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Average sunshine days in May
Portland, OR

Average sunshine days in May - Portland, OR
  • Average sunshine days in May: 14.8 days

Months with the most sunshine days are July and August (23.8 days).
The month with the least sunshine days is March (8.3 days).

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Average UV index in May
Portland, OR

Average UV index in May - Portland, OR
  • Average UV index in May: 4

The month with the highest UV index is July (UV index 6).
Months with the lowest UV index are January, February, November and December (UV index 2).

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Average cloud cover in May
Portland, OR

Average cloud cover in May - Portland, OR
  • Average cloud cover in May: 46

The month with the most cloud cover is February (Cloud cover 58).
The month with the least cloud cover is August (Cloud cover 23).

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Average visibility in May
Portland, OR

Average visibility in May - Portland, OR
  • Average visibility in May: 5mi

Months with the highest visibility are July, August and September (6mi).
Months with the lowest visibility are January, February, March, April, May, June, October, November and December (5mi).

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