How We Rate
Our rating system is designed by surfers, for surfers. No black boxes—here's exactly how we calculate conditions.
The Rating Scale
Epic / Good
Clean conditions, quality waves. Get out there.
Fair
Surfable conditions. Not perfect, but worth a paddle.
Poor
Choppy, weak, or blown out. For the dedicated only.
Flat
Nothing to ride. Time for a coffee instead.
What We Measure
Wave Height
Size matters, but it's not everything. We look at both swell height and wind wave height separately. Ground swell > wind chop.
Wave Period
The secret sauce. 10+ seconds means organized, powerful waves. Under 6 seconds is usually choppy wind swell. We weight period heavily.
Swell Direction
Each beach has an ideal swell window. We know if your spot faces SE and the swell is coming from the NE—you're in the shadow.
Wind Speed & Direction
Offshore wind = clean faces. Onshore = bumpy mess. We calculate wind quality relative to each beach's orientation, not just raw speed.
The Algorithm
Wave Score (0-65 points)
Combines wave height, period quality, and swell-to-chop ratio. A clean 3ft wave with 10s period scores higher than a choppy 5ft wave with 5s period.
Wind Score (0-35 points)
Based on wind direction relative to the beach, modified by speed. Light offshore = 35 points. Strong onshore = 5 points.
Final Rating (0-100)
Wave score + wind score, with caps for truly bad conditions (blown out, flat, or dangerously large).
Beach Orientation Matters
Every spot in our system has a configured beach orientation (the direction it faces). This is crucial because:
- âś“A SE-facing beach needs SE swell to light up
- âś“Wind from the NW is offshore for east-facing beaches
- âś“The same swell can be pumping at one spot and flat at another
This is why our ratings differ by spot—we're not just showing you buoy data, we're interpreting it for each specific beach.
Our Data Sources
Multi-Model Wave Forecasts
We blend three independent wave models to give you more accurate forecasts. Each model has strengths—by combining them, we reduce the chance of any single model leading you astray.
WaveWatch III
NOAA / NCEP
US government model. Great for detecting incoming swells and short-period wind events. Uses GFS wind data.
ECMWF WAM
European Centre
The European gold standard. Excellent medium-range accuracy (3-7 days). Often considered the world's best weather model.
Open-Meteo
Multi-model ensemble
Aggregates multiple sources with detailed swell component separation. Good baseline data.
How We Blend
Our algorithm compares all three models for each forecast hour and calculates a confidence level:
You can toggle between individual models in the Surf Graph to see how they differ.
Tide Data
NOAA CO-OPS — Official tide predictions for nearest stations
Water Temperature
Open-Meteo sea surface temperature data
AI Summaries
Claude by Anthropic — Generates plain-English forecast summaries from blended data
Buoy Data
NDBC buoys — Real-time wave observations where available
⚠️ A Note on Accuracy
No forecast is perfect. We're working with model data, not magic. Conditions can change rapidly, and local factors (sandbars, jetties, bathymetry) affect wave quality in ways no algorithm can fully capture. Use Howzit as a guide, but trust your eyes when you get to the beach. If it looks good, paddle out.