Average temperatures in May
Daytime temperatures usually sit between 68°F (20°C) and 79°F (26°C), depending on where you are, and nights tend to dip to around 50°F (10°C) to 64°F (18°C). It’s warmer than April but still feels manageable—especially if you’re planning to be outdoors a lot.
You’ll mostly get sunny days, though the north can still see a bit of rain here and there. Sea temperatures range from 63°F to 66°F (17°C to 19°C). That’s still pretty brisk, but some people are fine with it, especially in sheltered coves or with a wetsuit. May falls toward the end of spring, and daylight sticks around longer—usually between 10 and 14 hours—so there’s plenty of time to explore without rushing.
Porto and northern Portugal
In Lisbon and central Portugal, May brings steady warmth. Daytime highs usually land between 68°F and 75°F (20°C to 24°C), while nights cool down to around 54°F to 61°F (12°C to 16°C). Rain is possible but usually light. You can expect a lot of sunny days, which makes it a good time to explore the city on foot or take day trips to nearby towns. It’s also when beaches in this region start seeing more locals and travelers. See our guide to how many days you need in Porto.
Lisbon and central Portugal
Lisbon and Central Portugal experience mild and sunny days in May, with daytime temperatures reaching from about 68°F to 75°F (20°C to 24°C). Evenings provide a slight chill, with temperatures ranging from 54°F to 61°F (12°C to 16°C). Rainfall remains moderate, with an average of 40-60mm over the month.
The Algarve and southern Portugal
May in the Algarve usually feels like the beginning of summer. You’ll get daytime temperatures between 72°F and 79°F (22°C to 26°C), and nights stay comfortable at around 57°F to 64°F (14°C to 18°C). Rain is rare, and most days are dry and clear. While the sea is still cool—about 64°F (18°C)—you’ll start to see people back on the beaches. Even if you’re not swimming, it’s a nice time for sunbathing or walking along the coast without the intensity of the summer sun.
Madeira
Madeira’s climate stays fairly even year-round, and May is no exception. Daytime temperatures usually sit between 68°F and 75°F (20°C to 24°C), and nights hover around 59°F to 64°F (15°C to 18°C). Rain is light, and the island is especially green this time of year. The sea’s a little warmer than on the mainland, around 66°F (19°C), so if you’re thinking about swimming, this might be one of the better spots in Portugal to try it.