 Heat bursts are rare atmospheric phenomenon characterized by gusty winds and a rapid increase in temperature and decrease in dew point ( moisture ) . Heat bursts typically occur during night @-@ time and are associated with decaying thunderstorms . In association with wake lows , heat bursts are caused when rain evaporates ( virga ) into a parcel of cold dry air high in the atmosphere making the air denser than its surroundings . The parcel descends rapidly , warming due to compression , overshoots its equilibrium level and reaches the surface , similar to a downburst . 
