and the water receded steadily from the earth, and at the end of one hundred and fifty days the water decreased. (Genesis 8:3)The 150 days mentioned in Genesis 8:3 are also mentioned in the last verse of Genesis 7:
The water prevailed upon the earth one hundred and fifty days. (Genesis 7:24)What happened during these 150 days? Well... there are a couple different views.
Some think that these 150 days refer to the first 150 days of the flood. Others think that these 150 days occurred immediately after the first 40 days of rain.
The view that the the 150 days refer to the first 150 days of the flood has the most convincing evidence. One of the most convincing pieces of this evidence are these two specific dates: the second month, on the seventeenth day of the month (Genesis 7:11), and the seventh month, on the seventeenth day of the month (Genesis 8:4). These two dates mark out a period of exactly 5 months (150 days). Could it really just be a coincidence that these two dates mark out a 150 day period? Probably not.
The view that the 150 days occurred after the first 40 days also has a problem: it creates a contradiction. It creates the contradiction that water prevailed upon the earth (Genesis 7:24) and decreased steadily (Genesis 8:5) upon the earth at the same time.
And just to throw out a few more numbers (for fun), the 150 days referred to in Genesis 8:3 and Genesis 7:24 occurred about 1656 years after creation (2349 BC according to James Ussher's calculations).
Take a look at the chronology of the flood graphic below in order to see the complete chronology of the flood.
Chronology of the Flood: Water Decreases Steadily - Genesis 8:3-5
How God Stopped The Flood (Part 1) - Genesis 8:1-3
Noah's Patience - Genesis 7:24
Genesis 7:4-5 - 7 More Days
The Ark Comes To A Rest (Part 1) - Genesis 8:4
To view a larger version of this graphic click here.