Jamieson, Fausset and Brown on Jeremiah 36:30

30. He shall have none to sit upon the throne--fulfilled (2Ki 24:8, &c.; 2Ki 25:1-30). He had successors, but not directly of his posterity, except his son Jeconiah, whose three months' reign is counted as nothing. Zedekiah was not the son, but the uncle of Jeconiah, and was raised to the throne in contempt of him and his father Jehoiakim (Jr 22:30).

dead body ... cast out--(Jr 22:18, 19).

day ... heat ... night ... frost--There are often these variations of temperature in the East between night and day (Ge 31:40).