Jan A Wagenaar, Origin and Transformation of the Ancient Israelite Festival Calendar, Harrassowitz Verlag, Wiesbaden 2005, proposes that the Feast of Unleavened Bread was originally in the month of Iyar, not Nisan. He argues this by pointing out that the feast was originally at the time of the barley harvest (Exodus 9:31-32) and not assigned to a fixed date in the calendar. He asserts, citing D.C. Hopkins, The Highlands of Canaan: Agricultural Life in the Early Iron Age, SWBAS, Sheffield, 1985, that the climate of Iron Age Palestine is about the same as today’s. Then he notes that the barley harvest in the lowlands of what is now Israel begins at the beginning of May, and later in the highlands. For this he cites a study of Palestinian agriculture from the first half of the 20th century, G. Dolman, Arbeit und Sitte in Palästina, Gutersloh, 1928-1942. He quotes from Dolman 4 dates for the beginning of the barley harvest near Jerusalem: June 3rd, 1911, May 21 1913, May 16th 1921, and May 24th 1925. This is too late to fall consistently in the Babylonian month of Nisanu which in the time of Artaxerxes I (reigned 464 BCE-424 BCE) began as early as March 26th, though as late as April 23rd. (R.A. Parker and W.H. Dubber stein, Babylonian Chronology 626 B.C. - A.D. 75, Brown University Press, 1956).

The hypothesis that the Feast of Unleavened Bread could not have fallen always in Nisan in the late Iron Age depends on the proposition that the climate of modern Israel is the same as in the Iron Age kingdoms of Israel and Judah. Does anyone have access to climatological studies that would refute or confirm this? I found this study on-line, in which one author holds that

the climate of the eastern Mediterranean generally has fluctuated in a fairly narrow range since the latter half of the EB IV.

which would support Wagenaar’s hypothesis.

  • 2
    Is climatology of the Middle East in scope for this site?
    – mbloch
    Apr 5, 2021 at 3:20
  • There is not a question here, just the statement of an opinion Apr 5, 2021 at 9:37
  • 1
    @JoshK "Does anyone have access to climatological studies that would refute or confirm this?"
    – Double AA
    Apr 5, 2021 at 15:16
  • Upvoted for detail supplied in question.
    – The GRAPKE
    Apr 5, 2021 at 16:20
  • @mbloch Climatology as pertaining to Judaism is certainly in scope
    – b a
    Apr 6, 2021 at 20:46

2 Answers 2


I won't answer the question as stated. Instead I will address one premise of the question, which is actually very common with this type of question.

The question assumes that Pesach is supposed to be at the time of the regular barley harvest. This come from a mistaken understanding of the Torah.

The connection between Pesach and the barley harvest is from the Korban haOmer, which is described as the "first of your harvest." This offering is described in Leviticus 2:14, according to Rashi and Toras Kohanim. There it says that the barley must be roasted, according to Rashi, because it is still moist and אביב, just ripening, and if it weren't roasted it could not be ground.

This shows that the Omer offering is not brought at the normal time of the barley harvest, but before the barley is fully ripened and dry. This stage is reached today in late March, the time when Pesach is celebrated, even in the highlands.

We see here that when one has a correct understanding of the Torah according to Rabbinic tradition, there is no conflict between Torah and Science. This answers many, many questions of this type.

  • If practice changed, theory changed to keep up with practice. That the Rabbis had a theory according to which the barley did not have to be ripe does not invalidate Wagenaar's hypothesis. The author of Exodus 9:51 states that "the barley was in the ear". The crop was ripe enough that it could be ruined by a hailstorm. Apr 6, 2021 at 2:05
  • How does that show it was ripe? We see that there was something that started growing, but pounding down on a very immature barley sprout with a supernatural hail will kill it.
    – Mordechai
    Apr 6, 2021 at 18:55

This Wagenaar fellow seems to be ignorant of a basic fact about the Jewish calendar: the month of Nissan is determined by when Passover will fall out. That is, the Rabbis waited for the signs of spring, and then declared the month of Nissan. If there were signs the spring was delayed, they would add a second month of Adar before Nissan so that Passover and Nissan would be in the spring. Because the Jewish calendar has a flex month that in those days was determined on a yearly basis, even if Wagenaar is 100% right about the agricultural data, that just means that in those days they observed Nissan a month later. Over time as the seasons shifted, the calendar could shift with it.

  • I don't understand this argument. If the spring season began "later", so did the barley harvest...
    – Double AA
    Apr 5, 2021 at 20:10
  • According to Tosefta Sanhedrin 2:2, the year cannot be intercalated on the basis of the crops alone. One had to consider the fruit of the trees and the equinox. One could intercalate on the basis of two of the three. If this law was followed, the year would never have been intercalated solely on the basis of the ripeness of the barley. Apr 6, 2021 at 2:11

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