On what date did Genesis say the Flood began?

Genesis says the Flood began on the seventeenth day of the second month. The date appears after Noah and the animals enter the Ark and the narrative describes the waters breaking forth.

Genesis uses a calendar based on months rather than the modern January-to-December system. It does not identify the month with a modern calendar name in this passage, so converting the date into a fixed modern date would add information that the text does not provide.

The Flood account includes several carefully stated dates. The Ark comes to rest on the seventeenth day of the seventh month, the mountain tops become visible in the tenth month, and Noah leaves the Ark in the second month of his six-hundred-and-first year. These markers create a chronological framework around the catastrophe.

The date is easy to confuse with the date on which the Ark rests or the date Noah exits. Those are separate events in Genesis, and the seventeenth day of the second month identifies the beginning of the Flood itself.