In Genesis, how long did rain fall during the Flood?

In Genesis, rain fell for 40 days and 40 nights during the Flood.

Genesis 7:12 states that rain fell upon the earth for forty days and forty nights after Noah entered the Ark. The phrase is one of the best-known time periods in the Flood narrative and is repeated in the account’s description of the rising waters.

This period should not be confused with the entire duration of the Flood. Genesis also describes the waters prevailing for 150 days, followed by a long process of receding before Noah left the Ark.

The number 40 has a wider biblical pattern. Later biblical stories use periods of forty days or years in accounts involving testing, travel, waiting, or preparation, including Moses on Mount Sinai and Jesus’ wilderness fast in the New Testament.