Abstract: The characteristics of late spring frost,including the temperature decreasing range,average daily minimum temperature continues days,was analyzed based on late spring frost data from 9 stations in Hubei province from 1951 to 2010.Assessment model to forecasting late spring frost was established by using principal component analysis method.The results showed that the frequency of late spring frost in March generally decreased in Hubei province last 60years.The frequency of late spring frost in April decreased obviously during the 1980s and 1990s but increased in the first 10 years of this century.From decadal aspect,there was no clear trend in the average maximums temperature decrease,but it was greater in March than that in April.The minimum daily average temperature of late spring frost in March and April decreased slightly in the first 10 years of this century.The average duration of late spring frost decreased slightly from 1951 to 2010,as totally 4.1 days.

Key words: Late spring frost index, Late spring frost index, Grade classification, Impacts assessment