May is the perfect month to travel to The Algarve if you love the warm Algarve sun but want to avoid the hot 30+ temperatures in summer. It's warm enough for activities like exploring beaches, eating out, and swimming, but still mild enough to enjoy activities like hiking, horse riding, bird watching, and climbing!
Crete. Crete is the southernmost island in Greece and enjoys average May daytime temperatures of 23 degrees/74 Fahrenheit making it one of the warmest greek islands to visit in May. The water is usually warm enough for swimming and the weather is usually calm, with occasional showers.
In the north of the country, Porto is seeing highs of 54°F (68°C), though some showers are still to be expected, so go prepared. It's balmier and drier still as you move further south to Lisbon, where highs are notching 72°F (22°C) and there are just five days of rain to contend with.