San Francisco Bay makes its own weather, and the island sits in the middle of it. Whatever your phone says for downtown, expect Alcatraz to feel cooler and windier.
Seasonal pattern
| Season | Typical conditions |
|---|---|
| Spring | Mild, breezy, variable cloud |
| Summer | Cool, frequent morning and evening fog, strongest winds |
| Fall | Warmest and clearest of the year |
| Winter | Cool, rain likely, shortest operating day |
Wind chill on the crossing
The open deck can feel 15–20°F colder than the pier. A windproof outer layer matters far more than an umbrella, which the wind will destroy anyway.
Does weather cancel sailings?
Rarely. Ferries operate in normal Bay conditions; severe weather can cause adjustments. Check the current schedule on the day.
Weather and photography
Fog is not a failure — it produces the island's most atmospheric images. See the photography guide.
Frequently asked questions
Is Alcatraz cold?
Usually cooler than San Francisco itself, with persistent wind on the ferry and exposed paths.
What is the foggiest month at Alcatraz?
July and August typically bring the most persistent fog; September and October are clearest.