In Genesis's flood narrative, how many days and nights did rain fall on Noah's Ark?

In Genesis's flood narrative, rain fell on Noah's Ark for 40 days and 40 nights.

Genesis 7 describes the rain beginning after Noah, his family, and the animals entered the Ark. The 40-day period is one of the narrative's best-known numbers and is repeated in later biblical traditions as a symbol of an extended trial or period of testing.

The 40 days of rain should not be confused with the total time that the Flood waters covered the earth. Genesis gives additional time spans: the waters rose for 150 days, and the Ark eventually came to rest after the waters began to recede. Thus, 40 days refers specifically to the rainfall, not the entire voyage.

The wording comes from the biblical text rather than from archaeological measurements. Religious interpretations differ about how the Flood should be understood, but the stated rainfall duration in Genesis is clear.