The major factors influencing evaporation are pool surface area, water and air temperatures, humidity, and wind. Large pools evaporate more water. Differences between air and water temperatures increase evaporation; dry air absorbs more water than humid air, and wind disturbs the layer of warm air insulating the water’s surface.
Climate and pool size determine surface area, temperature, humidity and wind conditions as well as the times and degrees of variance in air and water temperatures. Other factors that affect evaporation rates are water and air pressure, the use of water heaters and pool covers, and splashing or other disturbances to the water.