It is the season.
Tonight, in west central Missouri [click on image to enlarge]:
F 9.0, 5.0 sec, ISO 400, 70 mm.
Canon 5D III, 2.8 70-200 mm.
F 9.0, 5.6 sec, ISO 400, 70 mm.
Canon 5D III, 2.8 70-200 mm.
F 9.0, 14.0 sec, ISO 400, 70 mm.
Canon 5D III, 2.8 70-200 mm.
F 9.0, 8.8 sec, ISO 400, 70 mm.
Canon 5D III, 2.8 70-200 mm.