Saturday morning looks like it has the potential to produce the first frost of the season in outlying areas! A cold high pressure is diving southeast from Canada and looks like it will be parked overhead Saturday morning. The cold air mass along with light winds should allow the mercury to plummet.
The record for 9/17 is 34º set back in 1984 (incidentally my birthday) and the earliest sub freezing low in the greater Hartford area was 30º on 9/20/1979. If everything breaks just right, dew points remain low, and winds drop to calm frost is possible in many outlying towns Saturday morning.
Though it will be unseasonably chilly at least it will be sunny!