California weather in September
September splits California wide open: Death Valley runs 108° afternoons while San Francisco tops out near 70°.
Based on 12 weather stations. Twelve stations from Death Valley to the Sierra — California holds most of the country’s climates inside one border, and no state needs its regions kept apart more than this one.
Southern California
Highs 74–85°, nights 56–66°, and 0.1 in of rain in a typical September.
| Place | Highs / lows | Wet days | The short version |
|---|---|---|---|
| Los Angeles | 83° / 64° | 0 | Santa Ana heat, empty beaches, the warmest water all year. |
| Anaheim | 85° / 65° | 0 | Still furnace-warm, but the school year thins the queues. |
| San Diego | 77° / 66° | 0 | Summer without the crowds, and the sky finally clears at dawn. |
| Santa Barbara | 74° / 56° | 0 | The clearest air and the warmest water of the year. |
Central Coast
Highs 71–75°, nights 52–54°, and 0.1 in of rain in a typical September.
| Place | Highs / lows | Wet days | The short version |
|---|---|---|---|
| Monterey | 71° / 54° | 0 | The peninsula's clearest month, and the warmest the bay gets. |
| Santa Cruz | 75° / 52° | 0 | The warmest month arrives just as everyone else leaves. |
Bay Area & Wine Country
Highs 70–80°, nights 51–56°, and 0.1 in of rain in a typical September.
| Place | Highs / lows | Wet days | The short version |
|---|---|---|---|
| San Francisco | 70° / 56° | 0 | Real summer, at last — locals call this the payoff. |
| Napa | 80° / 51° | 0 | Crush is on, and the whole valley smells like fermentation. |
The Deserts
Highs 102–108°, nights 74–79°, and 0.2 in of rain in a typical September.
| Place | Highs / lows | Wet days | The short version |
|---|---|---|---|
| Palm Springs | 102° / 74° | 0 | Still scorching, but the end is finally in sight. |
| Death Valley | 108° / 79° | 1 | Still punishing, though the nights finally let go a little. |
The Sierra
Highs 73–83°, nights 35–51°, and 0.3–0.4 in of rain in a typical September.
| Place | Highs / lows | Wet days | The short version |
|---|---|---|---|
| Yosemite Valley | 83° / 51° | 1 | Long light, thin crowds, and granite in perfect condition. |
| South Lake Tahoe | 73° / 35° | 1 | The crowds vanish and the aspens start to turn. |
Each place above has its own page for the full story — what the month feels like, what to pack, and whether the timing is right.