According to Genesis, the Flood waters prevailed for 150 days.
The figure appears in the chronology of the Genesis Flood narrative after the waters rise and cover the earth. Genesis says that the waters prevailed upon the earth for 150 days before God caused them to recede. This is a different measurement from the forty days and forty nights of rain.
That distinction is important because popular retellings often compress the entire story into a forty-day event. In the biblical account, the rainfall lasts forty days, but the high waters remain for much longer. The ark eventually comes to rest on the mountains of Ararat, and Noah waits through additional stages of recession, bird-sending, and drying before leaving.
The chronology is presented using Noah’s age and named months, creating one of the more detailed timelines in Genesis. Interpretations of the calendar details vary, but the stated 150-day period is a clear feature of the Masoretic text’s narrative sequence.