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Wind: Why the Forecast Lies Near Shore
💡 Forecasts describe the open-water gradient wind — sea breezes, funneling, and gusts can locally double it or reverse its direction.
A forecast gives you the gradient wind — the large-scale flow driven by pressure systems over open water. But near land, the actual wind on your boat can differ dramatically in direction and strength. The three culprits every skipper must anticipate are sea breezes, gusts, and terrain funneling.
A sea breeze forms on warm, sunny afternoons: land heats faster than water, warm air rises over the land, and cooler air flows in off the sea to replace it. This can add 10–15 knots blowing onshore that the synoptic forecast never mentioned — often building around midday and dying at dusk. It can reinforce, oppose, or completely mask the gradient wind.
Terrain funneling happens when wind squeezes through a gap — a valley, a headland, or between islands. Like a thumb over a hose, the same air must accelerate to get through, so a forecast 15 knots can become a real 25+ in the channel. Gusts are shorter bursts, often when stronger wind aloft mixes down to the surface or spills over a cliff or breakwater, hitting in sudden puffs 30–40% above the average.
The practical lesson: read the forecast as a baseline, then adjust for what the coastline and the time of day are doing. Reef early near cliffs and gaps, watch the water for dark gust patches, and expect the afternoon sea breeze to rewrite the picture entirely.