 Sarnia has a humid continental climate ( Köppen climate classification <unk> ) . Winters are cold with a few short @-@ lasting Arctic air masses that dip far enough south and bring with them daily high temperatures lower than − 10 ° C ( 14 ° F ) . Sarnia , while not quite located in the southwestern Ontario <unk> , sometimes receives large quantities of lake @-@ effect snow . Sarnia averages 112 @.@ 0 cm ( 44 @.@ 1 in ) of snow per year , while London averages 194 @.@ 3 cm ( 76 @.@ 5 in ) . 
