Jewish History: Biblical History: The Duration of the Flood:
How long did the Flood last?
The Flood began on the 17th of Cheshvan (see Gen. 7:11); the earth
became dry on the 27th of that month, the following year (Gen. 8:14).
Since 12 lunar months are about 354 days, the time from the beginning
of the flood to its end was about 365 days.
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