According to Genesis, the Flood waters prevailed over the earth for 150 days after the mountains were covered.
Genesis 7:24 states that the waters prevailed on the earth for 150 days. This figure is not the same as the 40 days and 40 nights during which rain fell, a separate duration mentioned earlier in the account. Genesis 8 then says God remembered Noah and describes the waters beginning to subside.
The narrative uses several time markers, including Noah’s age, dates in the flood year, and intervals between the dove’s flights. These details can make the chronology difficult to summarize. The 150-day figure specifically describes the period during which the waters prevailed, not simply the length of rainfall.