How to Read Buoy Data for Surfing

By Nick Peterson · Published 2026-08-31 · Part of the LazySurfer glossary

Quick answer: Check WVHT (wave height in meters) and DPD (dominant period in seconds). A reading of 1.5m @ 14s from a nearby buoy usually means surf worth driving for. Under 10s period, expect choppy conditions regardless of height. MWD tells you if the swell is angled at your beach — a direction that doesn’t match your spot’s exposure is a dead session no matter what the height says.

The fields on an NDBC buoy report

NOAA’s National Data Buoy Center (NDBC) publishes real-time readings for hundreds of buoys offshore. Each reading contains several fields. Here’s what matters for surfers:

Field	What it means	Surfer's rule of thumb
WVHT	Significant wave height (meters) — average height of the top third of waves at the buoy	Multiply by ~0.6 to estimate shoulder-to-face height at the beach (energy is lost from buoy to shore)
DPD	Dominant wave period (seconds) — period of the strongest energy band in the spectrum	14s+ is groundswell. 10–13s is borderline. Under 10s is wind chop.
APD	Average period — averaged across all wave energy in the spectrum	Usually lower than DPD; use DPD for surf decisions
MWD	Mean wave direction — compass bearing of the dominant swell (degrees true)	Compare to your spot’s ideal swell window. A NW swell (315°) hitting a south-facing beach = flat
WSPD / GST	Wind speed and gust at the buoy (knots)	Offshore wind at the buoy doesn’t always match onshore — use a coastal station for ground-truth
ATMP / WTMP	Air and water temperature	Useful for wetsuit selection, not surf quality

How to decide if a reading is worth driving for

Use this two-step filter before you load the car:

Period first: If DPD is under 10s, stop. The energy won’t survive the shelf and reach the beach with any shape. Height numbers are almost irrelevant below 10s period.
Direction second: Check that MWD falls inside your spot’s swell window. A spot that needs a SW swell (200–240°) won’t fire on a NW swell (300–330°) even if WVHT is 3m.

If both pass, then look at WVHT and do the rough beach-height estimate (WVHT × 0.5–0.7 depending on shelf geography). Combine with local tide and wind for a final call.

Which buoy to use for your spot

The closest offshore buoy isn’t always the best indicator for your break. A buoy that sits inside a bay or harbor reads sheltered water. Look for:

Buoys positioned upcoast in the primary swell window (e.g., NDBC 46042 for central California, NDBC 41047 for East Coast offshore)
Deep-water offshore buoys (water depth 1000m+) for the cleanest swell readings without refraction artifacts
Inshore buoys only for tide/current checks — they’re too sheltered for swell data

Spectral data: the next level

NDBC also publishes full spectral wave data — energy broken down by frequency band. This lets you separate a long-period groundswell from overlapping wind chop when both are showing up. Most surf apps simplify this into a single-number forecast. LazySurfer reads the raw spectral data directly from NDBC and uses it as one of the seven inputs to its similarity model.

How LazySurfer uses buoy data

LazySurfer reads live NDBC buoy readings for the stations nearest to each surf spot in its database — no intermediary forecast provider. It compares WVHT, DPD, MWD, wind speed, wind direction, tide height, and tide direction against the conditions you gave high ratings in your session log. When all seven parameters land close to your historical sweet spot, you get an alert. The full model explanation is here.

Related terms

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