In Genesis, the Flood waters prevailed for 150 days before the account says the Ark began to rest on the mountains of Ararat.
Genesis 7:24 states that the waters prevailed upon the earth for 150 days. Genesis 8 then says that God remembered Noah, caused a wind to pass over the earth, and that the waters subsided. The Ark’s resting on Ararat is recorded after this chronology advances.
This number is commonly confused with the 40 days and 40 nights of rain. The two figures describe different parts of the narrative: forty days concerns the rain, while 150 days concerns the period during which the waters prevailed. Genesis also supplies calendar dates for the Ark’s resting and Noah’s eventual departure.