The best times to visit Oklahoma City are April–June and September–October, when daytime temperatures sit in the comfortable 20–28°C range and the prairie around the city is at its greenest. July and August are hot — regularly above 35°C, often above 38°C — and the air is heavy with humidity. Winter is mild by Midwestern standards: cold snaps below freezing are common but not prolonged, and snow falls only a few days a year.
The city's signature weather feature is the springtime severe-thunderstorm season, mid-April through May, when supercells regularly produce hail, damaging winds, and tornadoes. Hotels stock weather radios, every public building has a posted storm shelter, and a city-wide siren system is tested at noon every Saturday. It is not dangerous to visit during tornado season — fatalities are rare — but it is worth keeping an eye on the local weather forecast.
The OKC Memorial Marathon runs in late April and is the largest annual event in the city; Festival of the Arts (also late April) and deadCenter Film Festival (June) are the main cultural events. The Oklahoma State Fair, in mid-September, fills the fairgrounds in the west of the city for two weeks of livestock, food and fireworks.