This is a list of surnames in which the categories include months.
AverillEnglish From Middle English aueril, Old French avrill meaning "April", perhaps indicating a person who was baptized in that month.
JanvierFrench Either from the given name Janvier or the French word janvier meaning "January", perhaps indicating a person who was baptized in that month.
MajewskimPolish Derived from Polish maj meaning "May". It may have been given in reference to the month the bearer was baptized.