Rates surfing and bodyboarding at your beach from the swell, the swell period and whether the wind blows offshore or onshore. GoDay works out which way your beach faces (you can correct it), then finds the best 2 hours of each day.
Also on the page, but not in the score: wind direction, which way the beach faces, tide (a model estimate).
A storm holds the score at 2, and one due within two hours at 4. A flat day (under about 0.3 m of surf) holds it at 2, and swell too big to surf (over about 4 m) at 3. An onshore wind over 30 km/h (19 mph) blows it out and holds it at 3.
Daylight counts too: at dusk the score is held at 5, and once it's dark at 1.
GoDay rates about 0.8 to 2 m (2.5 to 6.5 ft) of surf at your beach as good. It scales the swell by how square-on it hits the beach, so a big swell from the wrong direction can still be tiny.
Longer-period swell (10 seconds or more) carries more energy and arrives as cleaner, more powerful waves. Under 6 seconds it's wind chop.
Offshore wind, blowing from the land out to sea, holds the waves up and grooms them clean. Onshore wind crumbles them. Light wind from any direction is glassy, which is best of all.