Most interpreters use the Babylonian Calendar in applying Julian calendar dates to Biblical ones. This is anachronistic for the era before the end of the captivity: the first explicit mention of Babylonian-derived month-names being in year 2 of Darius the Persian (unless, like me, you place the time of Esther before then, but the dates in that book applied to Susa and the Medean Empire). That this usage is wrong in Judah, at least before the destruction of the first temple, can be proved by comparing Biblical days of the week with those in the Nisan Calendar for the fall of the city and the Temple.
There are four named months in the new calendar Moses instituted at the time of the Exodus: Abib (or Aviv) for Month I in spring (Exo.13:4) and then, in the time of Solomon we find names for months II: Zif, VII: Ethanim and VIII: Bul.
In addition, the Passover and Crucifixion narratives in the gospels can only be reconciled when it is realised that the gospel writers, referred to two calendars that differed in that year and month by one day. 1
These considerations mean that, whenever a Biblical date records the month and day, we cannot be sure which is the appropriate calendar to use unless the month is specifically named.
There has been much discussion in the literature as to whether Jerusalem fell and the temple was destroyed in 587 or 586 BC. I believe both schools are right - and both are wrong! The Biblical date for the fall of the city was 9/IV in Zedekiah's 11th Year and 9/V in Nebuchadnezzar's 19th year for the destruction of the temple. However in month VII, after the fall of Jerusalem, Ishmael killed some pilgrims who were bringing offerings for the Temple, presumably for the Day of Atonement and to attend The Feast of Tabernacles. Therefore the Temple must still have been standing in month VII after the fall of the city. It follows that there must have been at least a year and a month between the first two dates.
The Talmud states that the Temple was set alight just after the Sabbath ended and it burned all night and all day, by the end of which it was completely destroyed. Thus 9/V was a Sunday (defining the day at noon to make the weekday the same in both the western and Judean calendar, which latter starts the new day of the week after sunset). My implementation of the Exodus calendar now agrees with 9/V being a Sunday, showing that month V started on a Saturday. This differs from my published pattern.2
The Jews commemorate this, and other disasters with a fast on 9/Av in their Babylonian-type calendar, in which the day of the week in a particular month varies from year to year. However, though they may now use a more modern calendar, they would not have forgotten that it happened soon after the end of the Saturday Sabbath. Chronologists need therefore to take account of the weekday in this instance.
In 586 BC, 9/Duzu (Tammuz) was a Thursday3 so that date cannot be correct. In 587 BC however 9/Abu (Av) was a Sunday, but in accepting this date for the Temple destruction, one must push the capture of the city back a year and a month to 588 BC, as shown above, but that causes other chronological conflicts.
1 Cragg, Martin A. (2018) The Passover and Day of The Crucifixion.
biblewitness.org/passover.htm
2 Cragg, Martin A. (2019) A Pre-exilic Hebrew Solar-Lunar Calendar.
Academia.edu, ReseachGate.net (although at 17 April 2021 all my posted calendrical papers are out of date in terms of month patterns. The calendar is a work-in-progress and the latest update is available at biblewitness.org/calendars.htm).
3 Babylonian Chronology 626 B.C. - A.D. 75, Richard A. Parker and Waldo H. Dubberstein, Reprint by Wipf and Stock 5/1/2007 (sic) - presumably US format.
©2021 Martin Allen Cragg