In Genesis, the floodwaters prevailed on the earth for 150 days before beginning to recede.
Genesis 7:24 states that the waters prevailed for 150 days, and Genesis 8:3 then says that they began to abate. This is a different time marker from the 40 days and 40 nights of rain. The rain describes the precipitation period, while the 150 days describe the continued dominance of the floodwaters.
The Flood narrative contains several chronological notices, including the date Noah entered the ark, the date the ark rested on the mountains of Ararat, and the later dates when the mountain tops became visible and Noah left the ark. These details create a structured timeline rather than one single duration.
Readers sometimes add the 40 days of rain to the 150 days of prevailing waters, but the text does not present them as two simple consecutive periods. The 150-day statement belongs to the waters’ prevailing phase after the rain began.