Spring is the obvious season — late April and early May see the azaleas at Winterthur in full bloom, the dogwoods through the Brandywine Valley, and the gardens at Longwood, Nemours, and Gibraltar at their peak. Temperatures are mild (15–22°C) and the days are long.
Summer is humid but works for outdoor concerts (the Clifford Brown Jazz Festival in June), baseball at Frawley Stadium, and the Longwood fountain shows. Autumn brings vivid foliage through the Brandywine Valley — peak colour is usually late October. Winter is grey and chilly but a good time for the museums and the Longwood Christmas display.