The source of a swell determines which surf spots will get waves and which ones will be flat. When weather forecasters indicate a swell direction (west, south, etc.), they refer where the swell is coming from. Swell direction is often measured in degrees where 90° is from the east, 180° is from the south, 270° is from the west and 0/360° is from the north. Each surf break will have a swell “window” from which it can receive waves. For instance, at Rincon Point in Santa Barbara, California, the narrow swell window between 250° and 290° is due to the south-facing coastline and offshore islands that block southern swells. This means that Rincon breaks best during westerly winter swells.