A method for determining wave height by means of a radar carried by an aircraft, the method implementing the following steps: a first step of pointing the antenna of the radar; a second step of determining the clutter acquisition plan according to the altitude of the aircraft; a third step of determining, for each clutter zone defined by the acquisition plan, two Doppler parameters PARA1 and PARA2 characterising the zone as a whole; a fourth step of calculating the average values of the parameters PARA1 and PARA2 over all of the zones in question; and a fifth step of estimating the wave height from the averages of the parameters PARA1 and PARA2. The wave height estimated in this way is transmitted to the aircraft and used to determine the conditions for the water landing of the aircraft.