Ember Days occur four times a year at the start of each Season. In Latin, they are known as the "quattuor anni tempora" (the “four seasons of the year”).
Traditionally observed by some Christian denominations, each set of Ember Days is three days, kept on a successive Wednesday, Friday, and Saturday. These three days are set apart for Fasting, Abstinence, and Prayer.
The first of these four times comes in Winter, after The Feast of Saint Lucia, 13 December; the second set comes with The First Sunday in Lent; The third set comes after Whitsunday/Pentecost Sunday; The fourth, and last set, comes after The Feast of The Holy Cross, 14 September. Their dates can be remembered by this old mnemonic:
“Sant Crux, Lucia, Cineres, Charismata Dia,
Ut sit in angaria quarta sequens feria.”
Which means:
“Holy Cross, Lucy, Ash Wednesday, Pentecost,
are when the quarter holidays follow.”