United States
Satellite: Sentinel-2 cloudless 2016 by EOX (CC BY 4.0). Outline and points © OpenStreetMap contributors / Natural Earth. North up.
In numbers
0.081km²
Area
1km
Coastline
41m
Highest point
0
People
14°C
Warmest sea
September
2km
To the mainland
When to go to Alcatraz Island
Best to visit from July to September.
The sea is warmest in September (14 °C) and coolest in April (12 °C). The water never reaches 21 °C: bring a wetsuit.
Averages 1991–2020. Sea: NOAA OISST, the water within 35 km of the coast. Air, rain and sun: NASA POWER. Best months weigh warm afternoons (23–30 °C), sea of 24 °C or more and few wet days.
Island in San Francisco, California, United States of America
Alcatraz Island is an island in United States. It covers 0.081 km², with 1 km of coastline. Its highest point rises to 41 m. Nobody lives on it. The nearest mainland is 2 km away.
Getting there
- Oakland San Francisco Bay Airport (OAK)nearest airport with scheduled flights · 21 km in a straight lineCar hire at OAK airport (Oakland)Discover Cars · Affiliate link↗
- FerriesAlcatraz - Pier 33 Alcatraz Landing
- 2 km from the mainlanddistance to the nearest continental coast
- From July to Septemberbest months to go (from 30 years of averages)
Plan the trip
Ferries, stays and things to do
Some links above are affiliate links: if you book through them we may earn a commission, at no extra cost to you. It never changes what the data on this page says.
On the island
What you find on Alcatraz Island.
- 2viewpointsAlcatraz
- 1lighthousesAlcatraz Island Lighthouse
- 1ferry terminalsAlcatraz Ferry Terminal
- 2ruins and archaeological sitesWarden's House
Counted in OpenStreetMap, the map anyone can edit, inside the island's outline. A low number may only mean nobody has mapped it yet.
The shape of the land.
On average the island stands 20 m above the sea. 100 % of it is below 200 m.
- 100 %0–50 m
Share of the island's area in each altitude band, from the Copernicus DEM (30 m, read at 30–240 m on large islands).
Month by month
The weather on the island.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Afternoon high (°C) | 13 | 14 | 15 | 16 | 19 | 21 | 22 | 22 | 23 | 21 | 17 | 13 |
| Night low (°C) | 6 | 7 | 8 | 8 | 9 | 11 | 12 | 12 | 12 | 11 | 8 | 6 |
| Sea (°C) | 12 | 12 | 12 | 12 | 12 | 12 | 14 | 14 | 14 | 14 | 13 | 12 |
| Rain (mm) | 100 | 102 | 82 | 42 | 18 | 6 | 1 | 1 | 4 | 29 | 62 | 138 |
| Wet days | 11 | 11 | 10 | 6 | 4 | 2 | 0 | 0 | 1 | 4 | 8 | 12 |
| Sun h/day | 5.1 | 6.3 | 7.6 | 9.6 | 11.5 | 13.3 | 13.3 | 12.0 | 10.7 | 8.5 | 6.4 | 4.6 |
| Wind (km/h) | 12 | 13 | 13 | 14 | 14 | 14 | 13 | 13 | 12 | 11 | 11 | 12 |
Averages 1991–2020 for the ~55 km NASA POWER cell over the island; the sea from NOAA OISST.
Recent years
Warmer and cooler years at sea.
Each month's sea temperature compared with its 1991–2020 average, in degrees.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2020 | +0.3 | −0.3 | +0.4 | +1.0 | +1.0 | +1.4 | +0.7 | +0.5 | +0.7 | +0.6 | −0.3 | −0.9 |
| 2021 | −0.8 | −0.9 | −1.5 | −0.6 | −0.8 | +1.2 | +0.8 | +1.5 | +1.2 | +0.3 | +1.4 | ±0.0 |
| 2022 | ±0.0 | +0.1 | −0.7 | −0.6 | −0.8 | +0.2 | ±0.0 | +0.8 | +0.8 | +0.7 | −0.9 | −0.9 |
| 2023 | +0.2 | −0.9 | −1.2 | −0.8 | +0.6 | +1.8 | +0.1 | +0.9 | +1.2 | +1.5 | +0.8 | +1.3 |
| 2024 | +1.0 | +1.5 | +1.2 | +0.9 | +0.1 | +0.2 | +1.5 | −0.1 | +0.4 | +0.8 | −1.0 | −0.1 |
| 2025 | ±0.0 | ±0.0 | −0.2 | +0.6 | −0.2 | ±0.0 | +0.6 | +0.5 | +1.7 | +2.3 | +1.3 | +1.2 |
+1 warmer than usual −1 cooler than usual
Photos
Seen by visitors.
Nearby
More islands nearby.
About these numbers
| Names, area, population | Wikidata (Q131354) · CC0 |
|---|---|
| Outline | © OpenStreetMap contributors · ODbL |
| Sea temperature | NOAA OISST v2.1 · 1991–2020 |
| Climate | NASA POWER · 1991–2020 |
| Relief, 3D model | Copernicus DEM GLO-30 · © DLR e.V., © Airbus Defence and Space GmbH, Copernicus/ESA |
| Beaches, ports, lighthouses, trails | © OpenStreetMap contributors · ODbL |
| Towns | GeoNames · CC BY 4.0 |
| Images | EOX Sentinel-2 cloudless 2016 · CC BY 4.0; Wikimedia Commons |
Every figure is an average, an estimate or a count from a public dataset. Licences and methods: data sources.
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