May weather forecast
Lisbon, Portugal

The arrival of May marks the onset of the city’s summer season. Despite the rainfall decreasing to 54mm in May, sporadic showers continue to maintain Lisbon’s lush landscapes. Gradually, the city begins to warm up with temperature highs moving past the 20°C mark. This is a time when locals and visitors can enjoy the city’s beaches, although the sea temperature remains a bit on the cooler side. Longer daylight hours combined with a high UV index promise gloriously sunny days, perfect for sightseeing and outdoor activities.

Temperature

Lisbon sees the arrival of May with an average high-temperature of an agreeable 22.1°C, indicating a subtle variation from April. Lisbon temperatures generally rest at a low of 13.9°C during the May nights.

Rainfall

In Lisbon, in May, it is raining for 8 days, with typically 54mm of accumulated precipitation. Throughout the year, in Lisbon, there are 112 rainfall days, and 774mm of precipitation is accumulated.

Sea temperature

In Lisbon, the average seawater temperature in May is 17.4°C.
Note: For swimming, a surface water temperature of 17.4°C is not enjoyable for the majority. It is not considered safe, as controlling breathing becomes progressively more difficult as water temperature decreases below 21°C.

Daylight

The average length of the day in May in Lisbon is 14h and 18min.
On the first day of May in Lisbon, sunrise is at 06:39 and sunset at 20:28. On the last day of the month, sunrise is at 06:13 and sunset at 20:54 WEST.

Sunshine

The average sunshine in May is 9h.

UV index

In May, the average daily maximum UV index in Lisbon is 8. A UV Index reading of 8 to 10 represents a very high threat to health from exposure to the Sun's UV rays for ordinary individuals.
Note: A typical high UV index of 8 in May suggests the following recommendations:
Prioritize protection; rapid damage can occur to unprotected eyes and skin. The Sun's UV radiation is at its strongest between the hours of 10 a.m. and 4 p.m. Minimize direct exposure to the sun during this period. For a sun-safe wardrobe, go for clothes that are tightly woven and generously sized.