Swell Intel

Introducing Wave Charts: Real-Time Offshore Wave Height Visualization

By Martin Kennedy

Introducing Wave Charts: Real-Time Offshore Wave Height Visualization

See the swell before it hits the beach.

We're excited to announce our newest feature: Wave Charts — an interactive offshore wave height heatmap that gives you a bird's-eye view of incoming swells across the entire coastline.


What is Wave Charts?

Wave Charts transforms raw ocean data into a beautiful, color-coded visualization showing wave heights across hundreds of miles of open ocean. Instead of checking individual surf spots one by one, you can now see the entire swell field at a glance.

The heatmap displays wave heights from flat (dark blue) to triple overhead+ (deep red), updating in real-time as conditions change.


How It Works

Color Scale

Color Wave Height Description
Dark Blue < 0.5 ft Flat
Blue 0.5 - 1.5 ft Ankle high
Green 1.5 - 2.5 ft Knee high
Lime 2.5 - 3.5 ft Waist high
Yellow 3.5 - 5 ft Chest to head
Orange 5 - 6 ft Head high+
Red 6 - 8 ft Overhead
Dark Red 8 - 10 ft Double overhead
Maroon 10+ ft Triple overhead+

5-Day Animated Forecast

Use the timeline slider at the bottom to scrub through 120 hours of forecast data. Watch swells build, peak, and fade as they approach the coastline. Hit play to animate the entire forecast and visualize swell movement in real-time.

Coverage Areas

Wave Charts covers all major US surfing regions:

  • West Coast: Southern California, Central California, Northern California, Oregon, Washington
  • Hawaii: North Shore and South Shore exposures with 500+ miles of offshore coverage
  • East Coast: New England, New York/New Jersey, Mid-Atlantic, Carolinas, Georgia, Florida
  • Gulf Coast: Texas to Florida Panhandle
  • Great Lakes: Michigan, Erie, and Superior

Why This Matters for Surfers

1. See Swells Before They Arrive

Traditional forecasts tell you what's happening at the beach. Wave Charts shows you what's happening offshore — often 200-500 miles out. Watch swells travel across the Pacific or Atlantic before they reach your local break.

2. Compare Regions Instantly

Planning a surf trip? Zoom out and compare wave heights across entire coastlines. See whether NorCal is firing while SoCal is flat, or if the Gulf is picking up while Florida's Atlantic side stays small.

3. Understand Swell Direction

The heatmap's gradient naturally shows swell direction. Watch the color bands move toward shore to understand which breaks will light up first and which might be shadowed.

4. Identify Windows

The 5-day animation helps you identify the best windows in an incoming swell. See exactly when conditions will peak and plan your sessions accordingly.


Technical Details

For the data nerds among us:

  • Data Source: NOAA GFS-Wave model via Open-Meteo Marine API
  • Resolution: 0.25° grid (~25km / 15 miles)
  • Update Frequency: Hourly
  • Forecast Length: 120 hours (5 days)
  • Parameters: Significant wave height, wave period, wave direction, swell height, swell period

How to Use Wave Charts

  1. Open the Map: Navigate to the Maps page
  2. Select "Charts": Click the Charts/Spots toggle in the top right
  3. Explore: Pan and zoom to explore wave heights across different regions
  4. Animate: Use the timeline slider to scrub through the 5-day forecast
  5. Play: Hit the play button to watch the swell animation

What's Next?

This is just the beginning. We're working on:

  • Swell period overlay: Visualize long-period vs short-period swells
  • Wind overlay: See offshore vs onshore conditions
  • Custom alerts: Get notified when swells enter your region
  • Historical playback: Review past swells and compare to actual conditions

Try It Now

Wave Charts is available now for all users. Head to the Maps page and click "Charts" to start exploring.

Have feedback? We'd love to hear from you. Drop us a line and let us know what you think.

See you in the water! 🤙


Wave data provided by NOAA GFS-Wave model. Forecast accuracy decreases beyond 3 days. Always check local conditions before paddling out.