Harrisburg Weather in September

Harrisburg, Pennsylvania's capital, on the Susquehanna River at the eastern edge of the Appalachians has an interesting transitional climate. The Susquehanna provides humidity and flooding risk (the 1972 Agnes flood was catastrophic here) while the Appalachian ridges to the west create some weather modification. Three Mile Island's nuclear plant just south made the city world-famous for a near-disaster in 1979.

Excellent shoulder season — warm with fewer tourists in many destinations.