The objective of the paper was to characterise the climatology of surface temperature in the mid-winter months (DJF) in the northern part of Vietnam in the years 1971-2016 and determine the abnormal mid-winter warm spells and their statistic characteristics basing given criteria. The results shown that abnormal warm spells occur in January when the daily average air temperature is greater than 3o C in comparison with the given standard threshold (the sum of the climatological everage and standard deviation values of monthly mean temperature). | Research on the criteria to determining abnormal mid-winter warm spells in the northern part of Viet Nam
