In Genesis, how many days did rain fall during the Flood after Noah entered the Ark?

In the Genesis flood narrative, rain fell for 40 days and 40 nights after Noah entered the Ark.

Genesis 7:12 gives this duration after describing Noah, his family, and the animals entering the vessel. The number 40 is a recurring period in biblical literature, also appearing in accounts involving Moses and Jesus, although those episodes are separate from the Flood story.

The 40-day rainfall should not be confused with the total length of the Flood. Genesis also says that the waters prevailed for 150 days, and that the entire episode—from the beginning of the rain until Noah’s departure—lasted about a year according to the narrative’s dated sequence. Thus, 40 days describes the principal rainfall, not every day that the Ark remained afloat.

Genesis presents the event as a theological judgment and a new beginning. Other ancient Near Eastern flood stories use different durations, so their numbers should not be substituted for the figure in Genesis.