The story
Perhaps a calque of German Eisheilige; compare French saints de glace.
Etymology from Wiktionary, CC BY-SA 4.0.
ice saints
Today it means: The saints Pancras of Rome, Servatius of Tongeren, Mamertus of Vienne and/or Boniface of Tarsus, and sometimes Sophia of Rome, whose feast days are on May 11th though 15th. Full definition →