Most days of the year are pleasant. Winters (December–February) are mild, with daytime temperatures around 65°F and reliably clear skies for the racetrack's marquee meets. Spring is the best time for the Arboretum — California natives bloom, the roses come out, and the surrounding mountains are still green from winter rain.
Summers run hot. July, August, and September regularly hit 95–100°F, and the mountains become smog-traps for hot afternoons. Plan outdoor activity for mornings and head into the canyons (which are 10–15°F cooler) for hikes. Race meetings continue through summer but most visitors choose the cooler October–April calendar.