Understanding Buoy Data

Buoy data is essential for understanding ocean conditions and forecasting surf. Here's what the key measurements mean and how to interpret them.

Wave Height (Significant Wave Height - Hs)

Significant wave height is the average height of the highest one-third of waves measured during a time period (typically 20 minutes).

• Measured in feet or meters
• Represents what an experienced observer would estimate as the average wave height
• Individual waves can be up to 2x the significant wave height
• Example: If Hs = 4ft, some waves may reach 6-8ft

Why it matters: This is your primary indicator of wave size. Higher values mean bigger surf.

Wave Period

Wave period is the time interval between successive wave crests passing a fixed point.

There are several types of period measurements:

• Dominant Period (Dp): Period of the most energetic waves
• Average Period (APD): Average of all wave periods
• Peak Period (Tp): Period of waves with the most energy in the spectrum

• Longer periods (12+ seconds) indicate powerful swells from distant storms
• Shorter periods (6-10 seconds) suggest local wind waves or chop
• Long period swells travel faster and create better surf conditions

Wave Direction (MWD - Mean Wave Direction)

Mean wave direction indicates the compass direction from which waves are coming.

• Measured in degrees (0-360°)
• 0° = North, 90° = East, 180° = South, 270° = West
• Example: 270° means waves are coming from the west

Why it matters: Wave direction determines which beaches will receive the swell and how it will interact with local bathymetry and coastline features.

Putting It All Together

• Moderate to high wave height for your skill level
• Long period swells (12+ seconds) for powerful, organized waves
• Favorable direction that matches your local break's optimal swell window

• Hs: 5ft
• Tp: 14 seconds
• MWD: 280° (W-NW)

This indicates a solid west-northwest swell with good period - likely producing quality surf at west-facing beaches.

Additional Measurements

• Wind speed and direction: Affects surface conditions (clean vs choppy)
• Water temperature: Important for wetsuit selection
• Air temperature and pressure: General weather conditions

Understanding these measurements helps you make better decisions about when and where to surf.