Portland, ME weather in May
Expect cool weather with frequent rain in Portland in May, with highs near 64°F and lows near 46°F. Rain falls on about 13 days.
- Normal high
- 64°F
- Normal low
- 46°F
- Wet days
- 13
- 3.7 in total
- Muggy days
- 0
- dew point 65°F+
How May changes from start to finish
| May 1 | May 31 | |
|---|---|---|
| Normal high | 60°F | 69°F |
| Normal low | 41°F | 50°F |
| Chance of a wet day | 39% | 40% |
| Sunrise / sunset | 5:33 am / 7:43 pm | 5:02 am / 8:14 pm |
| Daylight | 14.2 h | 15.2 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Eastern Time).
A typical May day
- 6 am50°Fdew point 43°F
- 9 am57°Fdew point 44°F
- Noon61°Fdew point 44°F
- 3 pm60°Fdew point 44°F
- 6 pm57°Fdew point 43°F
- 9 pm52°Fdew point 44°F
NOAA hourly normals (local standard time) from Portland Intl Jetport (2 mi away); average wind 8 mph.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F12 of 31
- Beach dayshigh 80-95°F, under 0.05 in of rain, afternoon wind under 15 mph2 of 31
- Hot dayshigh 90°F or more0 of 31
- Muggy daysdaily mean dew point 65°F or more0 of 31
- Wet daysat least 0.01 in of rain or melted snow13 of 31
- Notable rainat least 0.10 in7 of 31
- Freezing nightslow 32°F or below1 of 31
- Snow on the groundsnow depth 1 in or more0 of 31
Average days per May, counted from daily records for each year 1991-2020.
Rain in May
Normal precipitation is 3.7 in; a dry May brings about 2.2 in and a wet one about 4.6 in (25th and 75th percentiles). About 3 days bring half an inch or more, and about 1 an inch or more.
How May varies from year to year
- Warmest May, 1991-20202015: average high 71°F
- Coolest May2005: average high 57°F
- Wettest May2006: 12.3 in
- Driest May2018: 0.8 in
- Highest reading93°F (May 18, 2017)
- Lowest reading28°F (May 1, 2000)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
May compared with April and June
| April | May | June | |
|---|---|---|---|
| Normal high | 54°F | 64°F | 74°F |
| Normal low | 35°F | 46°F | 55°F |
| Wet days | 11 | 13 | 12 |
| Comfortable days | 3 | 12 | 15 |
| Daylight | 13.4 h | 14.7 h | 15.4 h |
Highs change by +10°F from April and +10°F into June.
Nearby alternatives in May
- Warmer: Concord, NH72 mi · high 69°F · 12 wet days
How Portland ranks in May
- Normal high345th warmest of 378 cities; 4th of 5 in Maine
- Wet days301st driest of 378
- Comfortable days197th most of 339
What to pack for Portland in May
- A rain jacket or umbrella – rain on about 13 days
Heating and cooling
May has 325 heating degree days and 10 cooling degree days (base 65°F), 5% of the year's total heating and cooling demand.
Questions
How cold is Portland in May?
The normal high is 64°F and the normal low is 46°F. From 1991 to 2020 the coldest May reading was 28°F (May 1, 2000).
Does it rain a lot in Portland in May?
About 13 days in May have at least 0.01 in of precipitation, and the normal total is 3.7 in. The wettest May in 1991-2020 was in 2006 (12.3 in); the driest was in 2018 (0.8 in).
Is May a good time to visit Portland?
May ranks 3rd of 12 months on our comfort score for Portland (68 out of 100). It has about 12 comfortable days. The best months are June and September.
Where the numbers come from
- Temperature, rain, snowfall, snow depth, frost dates and humidity and wind by hour: Portland Intl Jetport (USW00014764), 2.4 mi WSW of the city center, 45 ft . NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: Portland International Jetport Airport (726060-14764), 2.8 mi WSW of the city center, 44 ft . Hourly observations, 1991-2020.
- Not available for this location: cloud cover (no station close enough or similar enough in elevation).