On what day of the second month did Genesis say the Noah's Ark flood began?

Genesis says the Noah's Ark flood began on the seventeenth day of the second month.

Genesis 7:11 gives a precise date for the beginning of the Flood: in Noah’s six hundredth year, in the second month, on the seventeenth day. It then describes the bursting of the great deep’s fountains and the opening of the heavens. This date is one of the narrative’s most exact chronological details.

The biblical text uses its own calendar framework, and interpreters debate how its months relate to later Jewish calendar systems. The safest answer is therefore the wording given by Genesis rather than a conversion to a modern calendar date.

The narrative also supplies later dates: the ark rests on the mountains of Ararat on the seventeenth day of the seventh month, and the earth is fully dry in Noah’s six hundred and first year. Those dates help structure the story, but they should not be confused with the seventeenth day of the second month when the Flood begins.