In Genesis, how long did rain fall during the Flood described in Noah's Ark?

In Genesis, rain fell for 40 days and 40 nights during the Flood described in Noah's Ark. This period appears in Genesis 7:12, after Noah, his family, and the animals entered the ark.

The number 40 is a recurring biblical period associated with testing, preparation, or transition. Other examples include Moses' 40 days on Mount Sinai and Jesus' 40 days in the wilderness, although those stories are separate from the Flood narrative.

The 40 days of rain should not be confused with the total duration of the Flood. Genesis also says that the waters prevailed on the earth for 150 days. The text therefore distinguishes the period of intense rainfall from the longer time during which floodwaters remained dominant.

Some retellings simplify the story by saying that it rained for 40 days and then the Flood immediately ended. In Genesis, however, the waters later recede, and Noah remains aboard the ark until the land becomes suitable for leaving.