Almost true again.

Spring may be in full swing, but May 11, 12, and 13 often revert to the colder days of winter, according to weather lore.

The Three Chilly Saints—Mamertus, Pancras, and Gervais (also called Mammertius, Pancratius, and Gervatius or Servatius)—often celebrated their feast days during a cold snap. Some called them the Ice Saints or Frost Saints, and many farmers held off planting until after the Three Chilly Saints’ days had passed.

Germans knew these days as the Iceman Days, and both the English and French watched for a late frost around this time. St. Boniface (May 14) and the chilly “blackthorn winds” were associated with them, too.

St. Pancras Day (May 12) never passes without frost.