Where does WaveSearch wave data come from?

Wave data comes from two sources: Open-Meteo (ECMWF WAM model) with coverage up to 15 days, and Copernicus CMEMS (EU Marine Service) which supplements with ocean currents and secondary swell data.

How is the 1-10 surf score calculated?

The score combines wave height (0-4 pts), dominant period (-1 to 3 pts), wind conditions (-2 to +2 pts), and secondary swell (-1 to +1 pt). Short periods are penalized. Crossed seas (direction difference > 45°) are penalized. Offshore wind adds points, onshore subtracts them.

How are tides predicted?

We use the Open-Meteo Marine API with the MeteoFrance SMOC model, which provides hourly sea level data for each beach's exact coordinates. High and low tide events are automatically detected from this data.

How often are forecasts updated?

Open-Meteo updates every 3 hours, Copernicus every 6 hours, and tides are recalculated twice daily. User alerts are evaluated every hour.

What does wave energy (kJ) mean?

Energy is calculated using the oceanographic formula E = 0.491 × H² × T² (where H is height and T is period). It indicates wave power: low values ( 300 kJ) indicate very powerful surf.

Surf Forecast Methodology in Perú

Open-Meteo

Marine & Weather API

Our primary data source comes from Open-Meteo, a free and open API that provides high-quality marine and weather data.

Marine API: wave height, swell period, wave direction, and sea surface temperature.
Weather API: wind speed and direction, gusts, UV index, and sunshine hours (15-day coverage).
Update frequency: every 3 hours
Coverage: 360 hours/15 days (waves and wind)
Source: ECMWF WAM model (waves) and NOAA GFS + ECMWF (wind)

Copernicus CMEMS

EU Marine Service

We complement with data from the Copernicus Marine Environment Monitoring Service (CMEMS), offering superior spatial resolution and extended forecasts.

Extended waves: significant height, peak period, direction, secondary swell.
Resolution: ~9 km (0.083°)
Update frequency: every 6 hours
Coverage: up to 240 hours (15 days)

Merge rule: for the first 72 hours, Copernicus supplements Open-Meteo data with additional variables. From 73 to 240 hours, Copernicus extends the forecast.

Wind data note: Copernicus Marine only provides wave and current data. Wind data comes from Open-Meteo Weather API, which covers the full 15-day forecast window. This means extended forecasts also include wind data for more accurate scoring.

Tide Prediction

Open-Meteo Marine API (MeteoFrance SMOC)

Tide data comes from the Open-Meteo Marine API, using the MeteoFrance SMOC model which provides hourly sea level height (sea_level_height_msl) for each spot.

Source: Open-Meteo Marine API, MeteoFrance SMOC model.
High/low tide detection: local maxima and minima are automatically identified from the hourly data, with parabolic interpolation for sub-hourly precision.
Per-spot data: each beach receives tide data based on its exact coordinates.
Update frequency: twice daily
Coverage: 7-day prediction

Peru has a microtidal regime (range ~0.05 to 0.80 m), with a mixed semidiurnal pattern.

Condition Scoring

Rating Algorithm 1-10

Each forecast hour receives a score from 1 to 10, calculated by adding points for different factors:

Wave Height (0-4 pts)

< 0.5m = 0 pts | 0.5-1.0m = 1 pt | 1.0-1.5m = 2 pts | 1.5-2.5m = 3 pts | > 2.5m = 4 pts

Dominant Period (-1 to 3 pts)

Uses the dominant/peak period (wave_period). < 8s = -1 pt (wind swell, messy) | 8-10s = 0 pts | 10-12s = 1 pt | 12-16s = 2 pts | > 16s = 3 pts

Wind (-2 to +2 pts)

Glassy (< 5 km/h): +2. Light wind (5-10 km/h): +1. Moderate wind (10-20 km/h): offshore +1, onshore -1. Strong wind (> 20 km/h): onshore -2, offshore -1. Wind data covers the full 15-day forecast window.

Secondary Swell (-1 to +1 pt)

If a secondary swell with height ≥ 0.3m and long period (≥ 10s) exists, +1 point is added. If the period is short (< 10s) and direction differs > 45° from the primary swell, -1 point penalty for crossed seas. If directions are similar (≤ 45°), no penalty is applied.

Rating by score:

Flat (1) Poor (2-3) Fair (4-5) Good (6-7) Epic (8-10)

Derived Metrics

Additional Calculations

From the base data, we calculate additional metrics to help you plan your session:

Wave Energy

Calculated using the standard oceanographic formula: E = 0.491 × H² × T² (kJ), where H is significant height and T is peak period. Color coding: gray < 50 kJ, green 50-150, orange 150-300, red > 300.

Wetsuit Recommendation

Based on sea surface temperature (SST). We suggest the appropriate neoprene thickness.

Moon Phase

We display the current moon phase, relevant for its influence on tides and general conditions.

Best Hour of the Day

We identify the time window with the best score within each day to optimize your session.

Community Data

User-Generated Content

Our community actively contributes to improving the available information:

Beach submissions: users can suggest new spots that are reviewed by moderators before publishing.
Edit suggestions: any registered user can propose improvements to existing beach information.
Community photos: user-uploaded photo gallery for each spot, moderated before publishing.

DHN Special Alerts

Directorate of Hydrography and Navigation - Peruvian Navy

We integrate special alerts for abnormal swell and strong winds published by the DHN, Peru's maritime authority. These are critical safety alerts for surfers and beachgoers.

Official source: Directorate of Hydrography and Navigation (dhn.mil.pe), a Peruvian Navy agency.
Alert types: abnormal swell (waves above normal) and strong coastal winds.
Zone coverage: Northern Coast (Tumbes to La Libertad), Central (Ancash to Ica) and Southern (Arequipa to Tacna). Alerts are only shown on affected spots.
Twice daily (7:00 AM and 7:00 PM)
Display: alert banner on each affected spot page, with intensity level (light, moderate, strong, very strong), validity period and link to the official PDF.

Important: DHN alerts are informational and do not replace personal judgment. In adverse conditions, prioritize your safety and always check the official source.

Update Summary

Source	Frequency	Coverage
Open-Meteo Marine	Update frequency: every 3 hours	360h (15d) — waves, period, direction, SST (ECMWF WAM)
Open-Meteo Weather	Update frequency: every 3 hours	360h (15d) — wind, gusts, UV
Copernicus CMEMS	Update frequency: every 6 hours	240h (10d) — ocean currents, secondary swell (supplements Open-Meteo)
Tide Prediction	Update frequency: twice daily	7d
DHN Special Alerts	Twice daily (7:00 AM and 7:00 PM)	Active wave and wind alerts by zone

Our Methodology