On August 21, 2017, residents of Rochester will see the Moon will pass in front of the Sun. It will take a few hours: first contact starts at 1:15 PM, the mid-point is at about 2:30 PM, and the last sliver of the Moon will leave the Sun at 3:51 PM.
From our vantage point, only 70% of the Sun's disk will be covered; if you'd like to see a total eclipse, you'll have to travel a thousand miles or so. Check out NASA's 2017 eclipse website.
Be sure you follow NASA's instructions for watching the eclipse safely!