These three consecutive days in May mark the feasts of St. Mammertus, St. Pancras, and St. Servatus. In the wine-growing districts of France, a severe cold spell occasionally strikes at this time of year, inflicting serious damage on the grapevines; some in rural France have believed that it is the result of their having offended one of the three saints, who for this reason are called the “frost saints.” French farmers have been known to show their displeasure over a cold snap at this time of year by flogging the statues and defacing the pictures of Mammertus, Pancras, and Servatus. Discuss
Source: The Free Dictionary