The unexpected and unseasonable snowfall that hit Maycomb in Chapter 8 took most of the town's citizens by surprise. Dick Avery blamed "bad children" like Jem and Scout for the snow, claiming that it hadn't snowed in town "since Appomattox." ("Appomattox" refers to the Virginia town in which General Robert E. Lee surrendered his Confederate army in 1865. Avery was wrong about it being the last time to snow in Maycomb, however.) Atticus told Jem and Scout that it was some of "the coldest weather since 1885," and this proved to be accurate. According to the town's telephone operator, Eula May, who made the public announcement that schools would be closed,
"... it has not snowed in Maycomb County since 1885." (Eula May, Chapter 8)
So, it had been four decades--about 40 years--since the previous snowfall in Maycomb.