Tevet (Hebrew: טֵבֵת, Standard Tevet; Sephardim/Yemenite/Mizrachim "Tebeth"; Ashkenazi Teves; Tiberian Ṭēḇēṯ; from Akkadian ṭebētu) is the fourth month of the civil year and the tenth month of the ecclesiastical year on the Hebrew calendar. It follows Kislev and precedes Shevat. It is a winter month of 29 days. Tevet usually occurs in December–January on the Gregorian calendar.
The Gregorian New Year's Day nearly always occurs in this month. Only rarely will it occur in either of the two neighbouring months (Kislev or Sh'vat).
25 Kislev—2 Tevet - Hanukkah – Or 3 Tevet if Kislev is short
10 Tevet - Tenth of Tevet (Asara beTevet) - (Fast Day)
Tenth of Tevet (Hebrew: עשרה בטבת, Asarah BeTevet), the tenth day of the Hebrew month of Tevet, is a fast day in Judaism. It is one of the minor fasts observed from before dawn to nightfall. The fasting commemorates the siege of Jerusalem by Nebuchadnezzar II of Babylonia—an event that began on that date and ultimately culminated in the destruction of Solomon's Temple (the First Temple) and the conquest of the Kingdom of Judah (today southern Israel).
The day has no relationship to Chanukka, but it happens to follow that festival by a week. Whether the 10th of Tevet falls 7 or 8 days after Chanukka depends on whether the preceding Hebrew month of Kislev has 29 or 30 days in the relevant year.
According to II Kings (25:1–25:4), on the 10th day of the 10th month (which is Tevet when counted from Nisan, the "first month" according to Exodus 12:1–2), in the ninth year of Zedekiah's reign (588 BCE), Nebuchadnezzar, the Babylonian king, began the siege of Jerusalem. Two and a half years later, on the 17th of Tammuz at the end of the eleventh year of Zedekiah's reign (586 BCE) Jeremiah (52.6–7), he broke through the city walls. The siege ended with the destruction of the Temple three weeks later, on the 9th of Av, the end of the first Kingdoms and the exile of the Jewish people to Babylon. The Tenth of Tevet is thus considered part of the cycle of fasts connected with these events, which includes: Shivah Asar B'Tammuz (17th of Tammuz) and Tisha B'Av (9th of Av).