The rains began to fall on the 17th of Cheshvan of the year 1656 from creation (2105), flooding the earth and rising above the highest mountains. Only Noah and his family survived, in the ark built to that end by Divine command, and a pair of each animal species, who entered with him into the ark.
The following is a chronology of the Flood, as indicated by the dates and time periods given in the Torah's account and calculated by Rashi: Cheshvan 17: Noah enters ark; rains begin. Kislev 27: Forty days of rain end; begin 150 days of water's swelling and churning, during which the water reaches a height of 15 cubits above the mountain peaks. Sivan 1: Water calms and begins to subside at the rate of one cubit every four days. Sivan 17: The bottom of the ark, submerged 11 cubits beneath the surface, touches down on the top of Mount Ararat. Av 1: The mountain peaks break the water's surface. Elul 10:Forty days after the mountain peaks becom visible, Noah opens the ark's window and dispatches a raven. Elul 17: Noah sends the dove for the first time. Elul 23: The dove is sent a second time, and returns with an olive leaf in its beak. Tishrei 1: Dove's third mission. Water completely drained. Cheshvan 27: Ground fully dried. Noah exits ark.
(This chronology follows the opinion of the Talmudic sage Rabbi Eliezer; according to Rabbi Joshua's interpretation, the Flood began on Iyar 17, and all above dates should be moved ahead six months.)
Total time that Noah spent in the ark: 365 days (one solar year; one year and 11 days on the lunar calendar).
Link: See the Torah's account of the Great Flood, Rashi's commentary, and insights and interpretations from sages, scholars and mystics through the ages on the Noach Parshah Page