San Bernardino has a classic inland Southern California climate — hot summers (often above 100°F), mild winters, low humidity, and reliable sunshine. The valley can bake between June and September; spring (March–May) and autumn (October–November) are by far the best times to visit. Winter is mild in the valley but can bring snow to the nearby mountain resorts.
The city's biggest event of the year is the Route 66 Rendezvous (traditionally held each September), California's largest classic-car show, which closes off downtown for a four-day run of classic rods, cruise nights, and live music. The Redlands Bicycle Classic each spring brings professional cycling to the neighbouring town of Redlands.