Genesis 8:5

The waters continued to recede until the tenth month, and on the first day of the tenth month the tops of the mountains became visible.

Qumran 4Q252, fr. I (Gen. vi, 3—XV, 17)

And the waters [con]tinued to abate until the [ten]th month, the first day of (the month) – the fourth day of the week—and the tops of the mountains appeared (viii, 5)

Jubilees 6:23-31

And on the new head of the first month, and on the new head of the fourth month, and on the new head of the seventh month, and on the new head of the tenth month are the days of remembrance, and the days of the seasons in the four divisions of the year. These are written and ordained as a testimony for ever.

And Noah ordained them for himself as feasts for the generations for ever, so that they have become thereby a memorial unto him.

And on the new head of the first month he was bidden to make for himself an ark, and on that (day) the earth became dry and he opened (the ark) and saw the earth.

And on the new head of the fourth month the mouths of the depths of the abyss beneath were closed. And on the new head of the seventh month all the mouths of the abysses of the earth were opened, and the waters began to descend into them.

And on the new head of the tenth month the tops of the mountains were seen, and Noah was glad.

And on this account he ordained them for himself as feasts for a memorial for ever, and thus are they ordained.

And they placed them on the heavenly tablets, each had thirteen weeks; from one to another (passed) their memorial, from the first to the second, and from the second to the third, and from the third to the fourth.

And all the days of the commandment will be two and fifty weeks of days, and (these will make) the entire year complete. Thus it is engraven and ordained on the heavenly tablets.

And there is no neglecting (this commandment) for a single year or from year to year.

10th Month's Gate

Henock 72:27-28 (from the Ethiopian text, numbering by R.H Charles)

27. And the sun has (therewith) traversed the divisions of his orbit and turns again on those divisions of his orbit, and enters that portal (1st portal) the thirty mornings and sets also in the west opposite to it. 28. And on that night has the night decreased in length by a ninth part, and the night has become eleven parts and the day seven parts.