Things you personally do by season (spring/summer/autumn/winter) that aren't holiday related:
Dust/de-cobweb walls and fans: fall and spring. Change air filters. Sprinkler system maintenance. Furnace maintenance. ‎- Jennifer D.
Switch from space heater to window-based AC unit. Pack winter clothes in the closet and take out summer clothes in the spring, and the reverse in the fall. Listen to bird song recordings to refresh my memory (in spring). ‎- John B.
Install/uninstall the window a/c. Depends if these are events or ongoing things, like watching football or baking potatoes or wearing sunscreen. Preterite or imperfect. ‎- Meg Vmeg
Get the fans/portable ac out of storage. ‎- Jennifer D.
There aren't seasons in Texas. ‎- Kristin
Start seeds (Jan or so if I'm on top of my game). Graft scions (late Jan or early Feb). Take trips to hot places (any cool period in what passes for winter around here). PT in the pool (late spring when the pool finally warms up enough). ‎- Spidra Webster
Early March: clean up the floor of the closet I use as a tornado shelter (there's winter things strewn about). Fall/spring bedding swap--flannel sheets and a wool blanket for cooler months; cotton sheets and blanket for warm. ‎- Kirsten
Spring: Move the garden hose reel back outside. Summer: Patio furniture back out to the deck. Fall: Voice inside my head: "Winter is coming." Winter: *frozen face emojii* ‎- Micah