According to Genesis, Noah remained in the Ark for over a year from the flood’s beginning until the earth was dry.
Genesis gives a detailed chronology using Noah’s age and calendar dates. The flood begins in Noah’s 600th year, on the 17th day of the second month. Noah and his family finally leave the ark in his 601st year, on the 27th day of the second month.
This means the time inside the ark was more than a year, not merely the 40 days and nights of rain. The rain lasted 40 days, but the waters continued to rise and later recede. Noah waited for the ground to dry before leaving, following God’s instruction.
The exact number of days depends on how the ancient calendar is interpreted, but the narrative’s year-and-date sequence clearly spans into the following year. This is one of the most commonly shortened details in retellings of the story.