In Genesis, the Flood waters prevail over the earth for 150 days before beginning to recede.
Genesis 7:24 states that the waters prevail for 150 days. Genesis 8:3 then says that the waters recede at the end of the 150 days. This figure is distinct from the 40 days and 40 nights of rain mentioned earlier, because the rainfall period and the period during which the waters remain dominant are different parts of the narrative.
The Flood chronology contains several additional markers, including the Ark’s resting on the mountains of Ararat on the seventeenth day of the seventh month. Interpretive discussions sometimes note differences in how the calendar references are arranged, but the 150-day statement itself is explicit in Genesis 7:24. Confusing it with the rainfall duration is one of the most common numerical mix-ups in summaries of the story.