Subject: Forecasting Occurrence of Radiation Frost withmeteorologicalMinimum Data, Case Study: Shahroud(Semnan Province)

Frost is one of the major climatic Hazards that creates irreparable damages in various communities every year. Amongst different kinds of frosts, radiation frost is very important; because of frequency occurrence and iscontrollable well with active protection methods in agricultural sector. Along with radiation frost monitoring,Precise forecasting of the minimum temperature and hourly estimation of its variations (trend) during the nights with frost event for starting and ending time determination of the active protection methods is satisfied.Therefore, using an experimental forecasting model, which can calibrate to meet local conditions and have a simple application, it seems essential. Thereafter, this study aimed at predicting the minimum temperature using a Polynomial model. In this paper, using hourly synoptic data of shahroud station for January, February during 1984-2010, dry temperature after sunset embedded for developing the prediction model of minimum temperature. Then, according to the predicted minimum temperature, the temperature trend during the night hours with radiation frost event was incident prediction., Pearson correlation coefficient value between observed and predicted minimum temperatures based on developed model was In the significant confidence level of high. The amount of root mean square error (RMSE) for the developed model is 0.2 °C for January.