The postexilic name given to the fourth Jewish lunar month of the sacred calendar, but the tenth of the secular calendar. Thus, in the Targum of Jonathan the expression “the tenth month” at Genesis 8:5 is rendered “the month Tammuz.” Tammuz was the name of a Babylonian deity. (Eze 8:14) The Bible record does not apply this name to the fourth month but merely refers to the month by its numerical order. (Eze 1:1) The name does appear, however, in the Jewish Mishnah (Taʽanit 4:6) and other postexilic works. The use of the pagan name Tammuz as applying to the fourth month, as well as the use of the other postexilic names, may have been only a matter of convenience among the Jews. It should be remembered that they were then a subjugated people, obliged to deal with and report to the foreign powers dominating them, and in view of this it is no strange thing if they utilized the names of the months employed by these foreign powers. The Gregorian calendar used today has months named after the gods Janus and Mars, and the goddess Juno, as well as for Julius and Augustus Caesar, yet it continues to be used by Christians who are subject to “the superior authorities.”—Ro 13:1.
This month, Tammuz, corresponded to part of June and part of July and, therefore, came in the growing heat of summer. By now the grapevines were beginning to yield their first ripe fruit.—Nu 13:20.
It was on the ninth day of this fourth month (Tammuz) that Nebuchadnezzar breached the walls of Jerusalem in 607 B.C.E. after an 18-month siege. (2Ki 25:3, 4; Jer 39:2; 52:6, 7) During the 70 years of exile that followed, the Jews customarily fasted on the ninth day of the fourth month in memory of this blow against Jerusalem. (Zec 8:19) However, following the second destruction of Jerusalem, in the year 70 C.E., the fast was observed on the 17th day of the fourth month, the day the walls of the temple were breached by Roman General Titus. There were no festivals appointed by Jehovah for this month.