Historic Average Water Needs Estimate. Using GDD.

This uses crop coeffcients at 21 growing degree day (GDD) that define the growth stage, and linear interpolation between these points for the chosen crop grown in Eastern Washington. Because these crop coefficients are scaled by the average temperatures at each station, there may not be enough growing degree days at the chosen station to finish the crop coefficient curve. You can try the set days of year if you prefer. Go here for more information.

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