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

May weather forecast and climate
Portland, ME

Dusk view of the lit skyscrapers of the Portland city in Maine
Dusk view of the lit skyscrapers of the Portland city in Maine
May, the last month of the spring, in Portland, is an enjoyable month, with average temperature ranging between max 63.5°F (17.5°C) and min 44.2°F (6.8°C).

Temperature

In May, the average high-temperature increases, from a fresh 53.2°F (11.8°C) in April, to a comfortable 63.5°F (17.5°C). In Portland, in May, the average low-temperature is 44.2°F (6.8°C).

Humidity

In May, the average relative humidity in Portland is 71.1%.

Rainfall

In Portland, during 12.6 rainfall days, 4" (101.9mm) of precipitation is typically accumulated. In Portland, during the entire year, the rain falls for 130.9 days and collects up to 47.3" (1200.3mm) of precipitation.

Snowfall

In May, in Portland, it doesn't snow. April is the latest month when it typically snows. In Portland, during the entire year, snow aggregates up to 61.9" (1572.3mm).

Ocean temperature

In Portland, the average water temperature is 46.6°F (8.1°C). Swimming in 46.6°F (8.1°C) is considered life-threatening. Even a few minutes in 55.4°F (13°C) water is uncomfortable, and swimming below 50°F (10°C) may cause total loss of breathing control and cold shock, depending on a person's physique.

Daylight

The average length of the day in May is 14.7h.

Sunshine

The average sunshine in Portland is 7.8h.

UV index

In Portland, the average daily maximum UV index in May is 7. A UV Index value of 6 to 7 symbolizes a high health risk from unprotected exposure to the Sun's UV rays for the ordinary person.
The daily maximum UV index of 7 interpret into the following advice:
Take precautions and utilize sun safety practices. Protection against the skin and eye damage is required. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. 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.

What is the temperature in May in Portland?

The average high-temperature, in May, in Portland, Maine, is 63.5°F (17.5°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, Maine, is 71.1%.

How many days does it rain in May in Portland?

In Portland, Maine, during May, the rain falls for 12.6 days and regularly aggregates up to 4" (101.9mm) of precipitation.

Does it snow in Portland in May?

In May, it doesn't snow. April is the latest month when it typically snows.

How cold is the water in May in Portland?

In May, the average ocean temperature in Portland, Maine, is 46.6°F (8.1°C). Swimming in 46.6°F (8.1°C) is considered life-threatening. Even a few minutes in 55.4°F (13°C) water is uncomfortable, and swimming below 50°F (10°C) may cause total loss of breathing control and cold shock, depending on a person's physique.

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

In May, the average length of the day in Portland, Maine, is 14.7h.

How long on average sun shines in May in Portland?

The average sunshine in May in Portland is 7.8h.

How high is the UV index in May in Portland?

In May, the average daily maximum UV index is 7. A UV Index of 6 to 7 symbolizes a high health threat from unsafe exposure to the Sun's UV rays.
Average temperature in May - Portland, ME
  • Average high temperature in May: 63.5°F

The warmest month (with the highest average high temperature) is July (78.8°F).
The month with the lowest average high temperature is January (31.2°F).

  • Average low temperature in May: 44.2°F

The month with the highest average low temperature is July (59.4°F).
The coldest month (with the lowest average low temperature) is January (13.4°F).

Average humidity in May - Portland, ME
  • Average humidity in May: 71.1%

The month with the highest relative humidity is September (76.7%).
The month with the lowest relative humidity is February (65.2%).

Average rainfall in May - Portland, ME
  • Average rainfall in May: 4"

Wettest months (with the highest rainfall) are October and November (4.9").
The driest month (with the lowest rainfall) is August (3.1").

Average rainfall days in May - Portland, ME
  • Average rainfall days in May: 12.6 days

The month with the highest number of rainy days is May (12.6 days).
The month with the lowest number of rainy days is September (9.2 days).

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

The month with the highest snowfall is January (19.2").
Months with the lowest snowfall are May, June, July, August, September and October (0").

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

The month with the highest number of snowfall days is January (7.9 days).
Months with the lowest number of snowfall days are May, June, July, August, September and October (0 days).

Average sea temperature in May - Portland, ME
  • Average sea temperature in May: 46.7°F

The best month for swimming (with the highest average sea temperature) is August (63.7°F).
The coldest month (with the lowest average sea temperature) is March (38°F).

Average daylight in May / Average sunshine in May - Portland, ME
  • Average daylight in May: 14.7h

The month with the longest days is June (Average daylight: 15.4h).
The month with shortest days is December (Average daylight: 9h).

  • Average sunshine in May: 7.8h

The month with most sunshine is July (Average sunshine: 9.1h).
The month with least sunshine is December (Average sunshine: 4.5h).

Average UV index in May - Portland, ME
  • Average UV index in May: 7

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