In the Book of Genesis, the Flood waters prevailed over the earth for 150 days.
This figure appears after the narrative describes the waters rising and covering the earth. Genesis says that the waters prevailed for 150 days before God caused a wind to pass over the earth and the waters began to recede. The statement gives the story a longer duration than the initial period of rainfall.
The 150-day period is therefore not the same as the 40 days and 40 nights of rain. Genesis presents several separate time markers: the rain, the rising waters, the resting of the ark, and the eventual drying of the ground. These details create a chronological sequence rather than one single duration.
Readers sometimes combine all the numbers into a 150-day voyage or a 40-day Flood. Neither summary captures the wording of Genesis precisely. The 150 days specifically describe how long the waters prevailed, while the complete stay inside the ark lasted longer.