An analysis was made of data from 47 stations at which evaporation had been measured by means of U.S. Weather Bureau class A pans protected by wire mesh. The stations represent different climatic conditions ranging from subhumid to arid. The stations are situated on the Mediterranean coast, in the desert (the Arava Valley), in valleys, in plains, and in mountains. The average relative evaporation in each month was found to be equal at all the stations and could be expressed as a sinusoidal function. The small deviations from the sinusoidal function make computation of correlations superfluous. As a result of this finding, it is possible to estimate the average evaporation rates for every month and for every location in the country by using one parameter (the amplitude of the sine function) and a map of average annual evaporation depths.