May is when the sea catches up with the year. It reaches 12°C, four degrees above March, and the difference between a 4/3 with a hood and a 3/2 without one is the difference between an hour and three.
The swell has not gone. Atlantic lows still cross in May and Llangennith still picks them up; what has gone is the wind that ruined them all winter, so the days that arrive tend to be usable. Between the temperature, the light until nine and the fact that nobody has started their summer yet, it is the best-value weekend of the Welsh year.
Rhossili Down and the walk out to Worm's Head are worth the drive on their own in May, which matters more here than it would elsewhere. Half the point of the Gower is that a flat weekend is still a good weekend.

