May is the changeover. The Atlantic lows have moved north for the summer, so the west coast is running on smaller and less frequent swell, and the nortada picks up from the start of the month. It is a thermal wind: it builds through the day, arrives around midday and blows side-onshore on everything that faces west.
From here until the end of September that clock decides the day. Get in early or go south: the Algarve's south-facing coast turns the same wind into an offshore, which is the reason it is named so often in summer. The water is at 16°C and climbing, so still a 3/2 at least.
