Abstract: Using the daily data from 162 weather stations,the spatial and temporal variations of maximum and minimum surface air temperature in Northeast China were studied under the highest level of freedom condition for the period from 1961 to 2015.The results show that the distribution of annual mean maximum and minimum air temperature are significantly affected by topography.It has good spatial consistency.The spatial distribution of the maximum temperature shows significantly zonal characteristics,while that of the minimum temperature shows local characteristics.The temporal trend exhibits an initial increasing and then changes to decreasing trend,and the transition point appears in 1997.From 1980 to 1997,the temperature shows an increased trend over the entire region,representing the first spatial distribution pattern.From 1998 to 2015,the temperature shows an "increasing in the north and decreasing in the south" trend,representing the second spatial distribution pattern.The probability density curves of the maximum and minimum temperatures move to high-value areas after 1997.After 1990,the probability of extremely high temperature shows an increasing trend,while that of extremely low temperature is a decreasing trend.

Key words: Maximum temperature, Minimum temperature, Extreme events