Weather window

A weather window is a forecast period in which wind, sea, and visibility stay inside the limits an operation needs, the gap a master waits for before committing to a passage or a marine job. It is defined by the operation’s limiting criteria: a maximum wind force, a maximum significant wave height, a swell direction, and a minimum visibility, each tied to the vessel or to the lift, tow, or transfer being done. The navigator reads successive synoptic charts to find when a depression has passed or a ridge builds, then weighs the window’s length against the time the operation needs plus a margin. Offshore work, heavy-weather avoidance, and towage all turn on getting the window right.