a gale is a very strong wind. the beaufort scale is a way to measure weather conditions. it is based on observations. the first level of the scale that uses the word gale is 7 beaufort (of a total of 13 steps). there are other definitions as well. the u.s. government's national weather service defines a gale as 34 to 47 knots (63 km/h to 87 km/h or 39 miles per hour to 54 miles per hour) of sustained surface winds. forecasters usually issue gale warnings when they think there will be winds of this strength.