Telltale

weather · sailing knowledge

Coastal wind: sea breezes, headlands, lees and inlets

Near the shore, the land shapes the wind. Each effect has a pattern you can look for, and the stations show which one is at work today.

By Telltale Team · Reviewed

Before you go

  1. Look at the chart for headlands, high shores and inlets along your course.
  2. Read the gradient wind from the marine forecast, then think about what the land does to it.
  3. Compare an exposed station with a sheltered one. Conditions
  4. On the water, watch for dark patches and other boats’ heel.

Sea breeze and thermal fill

On a clear day the land heats, the air over it rises, and sea air flows in underneath.

It usually starts late morning, peaks mid-afternoon and fades toward evening. A strong opposing gradient wind or thick cloud can stop it, and it often arrives earlier or later than the model has it.

Point Atkinson, 6 Oct 2026: forecast against measuredHourly mean wind at Point Atkinson on 6 October 2026, 08:00 to 16:00, against the HRDPS 12Z run. At 11:00 the station measured 11 kn gusting 15; the run had 1 kn.05101508:0010:0012:0014:0016:00fills inMeasuredHRDPS 12Zkn
Point Atkinson, 6 Oct 2026: forecast against measured. ECCC station Point Atkinson (hourly mean) against the HRDPS 12Z run (05:00 PDT). Real values from the committed snapshot.

References 1 2

Headlands

Wind squeezes and speeds up around a point.

Expect more wind and a lift or header just off the tip, and a light, shifty patch tucked in behind it.

Lees: rock and trees together

The shelter behind high land comes from the whole obstacle, terrain plus forest.

A rock headland with tall trees on it is taller, as far as the wind is concerned, than its rock alone. At Lighthouse Park, at Point Atkinson, the lee comes from both the elevated rock and the forest on top of it, and the light patch reaches further downwind than the rock alone would suggest. Cutting the corner through it is usually lighter and shiftier for longer than it looks.

Telltale Conditions over English Bay: Point Atkinson on the Lighthouse Park headland at the entrance, the English Bay buoy in open water, and Jericho on the south shore.
Point Atkinson sits on the Lighthouse Park headland; compare it with the buoy in open water to the south. Not for navigation.

Channelling and outflow

Steep walls turn the wind to run along an inlet.

Howe Sound is the local example: inflow up the sound by day, outflow down it at night and in the morning, with the strongest wind where it narrows.

Howe Sound inflow, 5 Oct 2026Hourly mean wind on 5 October 2026 at Pam Rocks and Squamish Airport, with the HRDPS 06Z run at Pam Rocks. Pam Rocks went from 2 kn at 10:00 to 12 kn at 13:00; the run had 3 kn.051008:0012:0016:00Pam RocksSquamishHRDPS 06Zkn
Howe Sound inflow, 5 Oct 2026. ECCC stations Pam Rocks and Squamish Airport (hourly mean) against the HRDPS 06Z run (23:00 PDT the night before).

Howe Sound

Convergence and divergence

Along a straight coast, the land can squeeze the wind into a band.

Friction over land slows the wind and backs it. Stand with the wind at your back: with the land on your right, the land air turns into the sea air and the wind is stronger in a band along the coast. With the land on your left, the two spread apart and the band is lighter. This holds in the northern hemisphere.

Shore bends and refraction

Wind crossing a shore turns to come more square off it.

Close in, expect a shift toward perpendicular to the shoreline. Along a bending shore that means the wind direction changes as you sail along it.

Gusts off high land

Under high shores, the wind arrives in bursts.

Air tumbling over steep land brings fast air from above down to the water. Watch for dark patches and be ready to ease.

Telltale Conditions with the Point Atkinson station open: an Observed row of hourly wind above rows for HRDPS, HRDPS West, HRRR and ECMWF, a spread row, and a note on which model has done best there lately.
In TelltaleMeasured against forecast, per station. Tap a station in Conditions to line up what it measured beside each model for the same hours, with the spread between the models and the one that has done best there lately. Open Point Atkinson
Sources and review

Official references checked on 2026-10-11. Product details and schedules change; the provider’s page is the current word.

Take it to the water

Check the stations before you leave, then record the sail for the debrief.

Open ConditionsRecord a sail