A model for estimating areal evaporation and transpiration is modified slightly to provide estimates of annual lake evaporation from monthly observations of temperature, humidity, and sunshine duration (or radiation) in the land environment. The model estimates tend to be higher than the more conventional estimates in humid areas and lower in arid areas, with the latter tendency particularly noticeable in the case of Lake Nasser on the Nile River. However, the results agree very well with comparable water budget estimates for Lake Hefner in Oklahoma, the Salton Sea and Silver Lake in California, Pyramid and Winnemucca lakes in Nevada, Lake Ontario on the border between New York and Ontario, and Dauphin Lake in Manitoba. They also compare reasonably well with energy budget estimates of the evaporation from Lake Mead on the border between Arizona and Nevada when the net inflow of heat is taken into account. A technique that provides such realistic results over a wide range of depths and environments with readily available data should prove very useful in water resource or environmental impact studies. Examples of such uses are provided by maps of Canada and the southeastern United States that show average annual values of the lake evaporation, and average annual values of the difference between the evaporation from a projected reservoir, and the combined evaporation and transpiration from the area before flooding.