The duration of low temperature in winter season is one of the important agrometeorological characteristiece in crop growing fields. This study was conducted to develop a method to estimate the duration of low- temperature with monthly meteorological data. Using daliy meteorological data from 61 observation sites from 1981 to 2010, we analyzed the relationships between the averages of monthly temoerature minima and the durations of low-temperature ranging from-15 to 5˚C, The monthly mean of the January minimum air temperature was appropriate for theestimation of the durations of low-temperature below 0˚C. We tested a simple second order equation to predict durations of low-temperature. To apply the equation to various temperature ranges, we suggested two different equations for the estimation of coefficients a and b, which are dependent on the base temperatures from -115 to 0˚C. Thevalidation of the equations using other daily meteorological datasets from 1971 to 2000 showed that they were appropriate for the range from-10 to 0˚C, but underestimated at-15˚C.