In the biblical account of Noah’s Ark, the floodwaters prevailed over the earth for 150 days.
Genesis first describes rain falling for 40 days and 40 nights, but that is not the entire duration of the flood. The text later says that the waters prevailed for 150 days before beginning to subside. This distinction is a common source of confusion because both numbers appear prominently in the story.
The narrative then describes the Ark resting on the mountains of Ararat and Noah waiting through additional stages as the land dried. Genesis gives several dated milestones using Noah’s age and the calendar, although interpretations of the chronology differ among religious traditions and translations.
The 150-day figure belongs specifically to the biblical flood narrative. It should not be confused with later flood traditions, such as the Epic of Gilgamesh, which uses different durations and details.