The rain (the dark area underneath part of the cloud in the picture) ahead has a squall (sudden increase in wind speed and often direction) with it. When this is coming for you, you get down some sails to be prepared for the much higher wind that you expect the squall to have. After a few minutes, it is generally over, and you tend to have the same wind speed and direction as you did before the squall. There is an old sailor’s rhyme about dealing with squalls: When rain comes before the wind, topsail sheets and halyards mind When wind comes before the rain, hoist your topsails up again Yesterday the wind varied from Force 0 to Force 7, as it was mostly a squally day requiring lots of sail changes. The wind direction was favorable, though, so that was nice.