AbstractThe main objective of this study is to evaluate the ability to forecast seasonal and non‐seasonal monthly reference plant water consumption (ET0) with the Box–Jenkins approach (autoregressive integrated moving average), the abbreviation of which is ARIMA (indicated as SARIMA for seasonal series). This target was achieved by using the necessary climate parameters obtained from the Ankara meteorology station to calculate the monthly ET0 data sequences by using the Penman–Monteith relationship. Of the 12 months’ non‐seasonal ET0 data, only 4 months achieved all the conditions expected in simulation after satisfying the stationary condition. The ARIMA (SARIMA) (1,0,1) (3,1,0) model produced the best results among all models providing the necessary conditions for the seasonal series. When comparing the results of ET0 estimation from this model to that of the non‐seasonal series, it was determined that using the seasonal series rather than making an estimate based on the non‐seasonal series provided more successful results, and the model giving the most successful forecast for the study is the SARIMA model above.