True Wind Direction

True Wind Direction (TWD) is the compass direction, referenced to true north, from which the wind is actually blowing over the water. It removes the effect of the boat’s motion, so it differs from the apparent wind seen by masthead instruments while underway.

For sailors, TWD is central to sail selection, laylines, reefing decisions, and choosing a safe, efficient course. It helps assess whether a route will be upwind, reaching, or running, and should be interpreted alongside True Wind Speed, True Wind Angle, and Wind Direction.

In PredictWind forecasts, TWD is shown in model data and GRIB displays as the direction the wind comes from, not where it is going. Weather Routing, Departure Planning, and high-resolution maps use it to compare models, anticipate shifts, and optimise passage timing.