Genesis says the Ark rested on the mountains of Ararat after 150 days of prevailing floodwaters. Genesis 7:24 states that the waters prevailed on the earth for 150 days, and Genesis 8:3–4 then says they receded until the Ark rested in the seventh month.
This interval is separate from the forty days and forty nights of rain. The rain is the period of intense precipitation, while the 150 days describe the continuing dominance of the floodwaters. The narrative then gives further dates as the waters diminish and the land dries.
Genesis 8:4 places the Ark’s resting point on the seventeenth day of the seventh month. Later, the text says that by the first day of the tenth month, the mountain tops were visible. Noah does not leave immediately; he waits for God’s instruction.
Different chronological readings discuss how the Hebrew calendar dates relate to the larger Flood timeline. The explicit 150-day statement remains distinct from both the rainfall period and the final waiting period.