Surf Spot Guide
Understanding Surf Forecasts
How to read swell periods, wave sizes, wind directions, and tide graphs to accurately forecast a session and stay safe.
Surf Forecasting Basics
A surf forecast is not a simple weather report. To determine if waves will be clean, messy, big, or flat, you must interpret three main forces: swell dynamics, local wind, and the state of the tide.
Swell Period Rule: Swell period (measured in seconds) is the most critical number on a forecast. Longer periods mean much faster, more powerful, and cleaner waves.
Deconstructing the Swell
- Swell Height: The height of the open-ocean waves in deep water. This is not the exact size of the breaking wave on the beach, which is heavily modified by local bathymetry (sea floor).
- Swell Period: The time it takes for two consecutive wave crests to pass a fixed buoy.
- Short Period (1-7s): Weak, wind-chop waves with poor organization. Commonly called "mushy" or "sloppy."
- Medium Period (8-11s): Standard groundswell. Solid, fun waves for beginners and intermediates.
- Long Period (12s+): Powerful groundswell. Waves travel from distant storms, packing high energy. Waves will break larger than the open-ocean height, creating heavy conditions.
- Swell Direction: The angle from which the swell is traveling. A surf spot must be open to this direction to receive wave energy.
Understanding the Wind
Wind determines whether wave faces are smooth ("clean") or bumpy ("choppy").
- Offshore Wind: Blows from the land out to sea. This grooms the wave faces, holding the crest up longer and creating clean, hollow shapes. Highly desirable.
- Onshore Wind: Blows from the sea onto the land. This crumbles the wave crests prematurely, causing messy, bumpy waves with poor power zones. Good for learning to stand up, but poor for clean rides.
- Sideshore Wind: Blows parallel to the beach, often creating cross-chop and strong lateral currents.
Tides and Break Dynamics
Tides determine water depth over reefs, sandbars, and rocks. They cycle every 6 hours and 12 minutes.
- High Tide: Deep water can cause waves to swallow their energy and "fatten up," making them difficult to catch, or break directly on the shore (shorebreak).
- Low Tide: Shallow water can cause waves to break fast and hollow, or "close out" (walling up and collapsing all at once). Exposed rocks or shallow reef heads become hazards.