Weather in Porto in May

How May compares

May is the 6th warmest month of the year in Porto and ranks 119th of 134 destinations we compare for May - see where else is hot in May. Within Portugal it is 11th of 13 (Portugal in May). Against London's average high of 16.6°C in May, Porto is 3.4°C warmer by day and 4.0°C warmer at night.

Daytime and night-time in May

The typical May day in Porto peaks at 20.0°C, but that is an average: the warmest 10% of days reach 25.7°C or more. Roughly 1 in 8 days top 25°C and 1 in 56 pass 30°C. Nights average 12.3°C; one night in ten drops to 9.3°C or lower, so pack a layer for evenings - it is genuinely cool after dark. Between 1991 and 2020 the hottest May day here reached 32.0°C (2009-05-30) and the coldest night 6.0°C (2001-05-01).

Rain in May

Wet (more than 8 rainy days): about 11 days with 1 mm or more, 102 mm in total. Year to year it varies a lot - the wettest May was 1994 with 271 mm, the driest 2003 with 7 mm. Humidity averages 77%.

Sea temperature in May

The sea averages 15.2°C - too cold for most (under 18°c). Depending on the year it ranges from 14.4°C to 16.0°C. For the warmest sea here, come in September (17.5°C).

Sunshine and daylight

Around 6.7 hours of sunshine a day (estimated from cloud cover), 14.3 hours of daylight: the sun rises about 06:16 and sets about 20:45 local time in mid-May. Average cloud cover is 53%.

Is May a good time to visit Porto?

May is not the strongest month here: warm days and frequent rain. The best months for Porto on our scoring are July, August, September; months averaging 25°C or more: Jul, Aug.

Comfortable days, cooler evenings

Porto's May temperatures suit spending time outdoors without planning everything around midday heat. A light top may be enough during warmer spells, but carry a layer rather than assuming that warmth will last into the evening. Nights average 12°C, and the coldest can fall to 9°C or below, so a jumper and jacket deserve space in your bag. There is a chance of something more summery: 12% of days reach 25°C, though days reaching 30°C are uncommon. That makes May a reasonable choice if you dislike strong heat, but a less convincing option if hot weather is the main reason for your trip. Pack for changeable spring conditions, not just the warmest afternoon.

Allow for rain, and treat the sea as cold

Rain is the compromise here. With about 11 rainy days, a waterproof jacket and shoes you are happy wearing in wet weather are more useful than an entirely fair-weather wardrobe. Keep outdoor plans flexible and have an indoor alternative, rather than relying on a dry stay. Rain does not mean constant gloom: May averages about 6.7 hours of sunshine within 14.3 hours of daylight, leaving plenty of light for exploring when conditions suit. The coast is a different proposition from the city air, however. At around 15°C, the sea is cold, not comfortably swimmable. Choose May for time outdoors between wet spells, rather than a holiday built around long sea swims.