When should I visit Los Angeles, United States, for the best experience?

Los Angeles has a genuinely dry summer and a genuinely wet winter, and the downtown record under the 1991–2020 normals makes the split stark. August averages a daily high of 84.0°F (28.9°C) and 0.00 inches of rain for the whole month; July manages 0.02 inches. February, the wettest month, averages 3.64 inches, with January close behind at 3.29 inches. Annual precipitation is 14.25 inches, almost all of it falling between November and March. The annual mean high is 74.8°F (23.8°C) and the mean low 56.8°F (13.8°C) — a narrow band that explains why the city has so little seasonal shutdown.

September is the hidden heat month. Downtown normals put it at 83.0°F (28.3°C), hotter than July's 82.0°F (27.8°C), which catches out visitors who assume summer ends with August. By October the high drops to 78.6°F (25.9°C), and that is the sweet spot.

Scheduling around the city's institutions matters more than scheduling around weather. Griffith Observatory, which is free to enter, is closed every Monday and opens at noon from Tuesday to Friday, moving to 10 a.m. on Saturdays and Sundays, with a 10 p.m. close every open day. The surrounding park's grounds and roads are generally accessible from 5 a.m. to 10:30 p.m.

The open country at the city's edge is on a different schedule again. Santa Monica Mountains National Recreation Area, established in 1978 and covering 153,075 acres, is described by the Park Service as the world's largest urban national park — and its trails are a cool-season proposition in a region this dry.

The marine layer is the thing no monthly average captures: through late spring and early summer, mornings on the coastal plain can be grey and cool while the inland basin is already clear and warm. By October that pattern has largely broken down, which is part of why the fall light here is so consistent.

Griffith Observatory's Monday closure is the most commonly wasted evening in Los Angeles, because the building is free and the view over the basin is the main reason people drive up. Note also that the observatory opens only at noon on weekdays — a morning plan does not work there at all, even on an open day — while the park roads around it open at 5 a.m.

• October on the coast — A normal high near 79°F with barely half an inch of monthly rain is as reliable as Southern California gets.
• Winter for the mountains — The 153,075 acres on the city's northwestern edge are walkable in the months when the basin is too wet for much else.
• Evenings on the hill — With a 10 p.m. close every open day, the observatory is the one major Los Angeles institution built around after-dark visiting.

The dry season has a cost. With essentially all of the year's 14.25 inches falling between November and March, the hills above the basin have gone months without rain by the time autumn arrives, and trail or road closures in the Santa Monica Mountains can follow. Drones are prohibited in all City of Los Angeles parks, including Griffith Park, and smoking and vaping are banned throughout it — relevant if you had plans for aerial footage over the basin. Alcohol in the park requires a permit. And the city's scale is the real constraint in any month: a day that pairs the observatory with the coast is two substantial drives, not one.

See the Los Angeles things-to-do question in this group for the city's World Heritage component and for Metro's fare caps, which change the arithmetic of crossing the basin.