The mountain tops became visible in the tenth month, according to Genesis 8:5. The verse says that on the first day of the tenth month, the tops of the mountains appeared as the floodwaters continued to decrease.
This detail belongs to a carefully sequenced chronology. Genesis says the ark came to rest on the mountains of Ararat in the seventh month, and the mountain tops appeared later, in the tenth month. The passage therefore distinguishes the ark’s resting from the later visibility of high ground.
The text uses numbered months rather than the familiar modern calendar names. Their exact seasonal relationship depends on the calendar system being assumed, and translations generally preserve the numbers rather than converting them into January, October, or another modern month.
The chronology continues after this event: Noah later tested the land with birds before removing the ark’s covering and eventually leaving it.