Tides Today & Tomorrow in Alcatraz Island, CA

TIDE TIMES for Friday, August 21, 2026
The tide is currently falling in Alcatraz Island, CA.
Next low tide : in 5m at 1:49 am (0.8 ft)
Next high tide : 9:32 am (4.1 ft)
Sunset today : 7:54 pm
Sunrise tomorrow : 6:30 am
Moon phase : First Quarter (66% illuminated)
Tide Station Location : Station #9414792
Common Questions About Tides

Alcatraz Island, CA Tides - Jul 1938

DateHigh TideLow TideSunMoonDate
AMftPMftAMftPMftRiseSet
1Fri1:306.03:085.68:04-0.88:401.94:507:35Waxing Crescent1Fri
2Sat2:295.43:555.88:51-0.29:511.74:517:35First Quarter2Sat
3Sun3:354.74:425.99:410.511:051.44:517:35First Quarter3Sun
4Mon4:524.25:316.010:351.24:527:35First Quarter4Mon
5Tue6:203.96:216.012:161.111:33 AM1.84:527:35First Quarter5Tue
6Wed7:503.97:096.11:210.712:342.34:537:34Waxing Gibbous6Wed
7Thu9:054.17:556.12:170.31:342.64:547:34Waxing Gibbous7Thu
8Fri10:044.38:386.13:050.02:282.84:547:34Waxing Gibbous8Fri
9Sat10:514.59:196.13:47-0.23:162.94:557:34Waxing Gibbous9Sat
10Sun11:324.69:576.14:25-0.34:002.94:557:33Full Moon10Sun
11Mon12:074.74:59-0.44:402.94:567:33Full Moon11Mon
12Tue12:394.75:31-0.45:192.94:577:33Full Moon12Tue
13Wed1:084.86:02-0.45:562.84:577:32Full Moon13Wed
14Thu1:374.96:32-0.36:342.74:587:32Waning Gibbous14Thu
15Fri12:255.62:065.07:02-0.17:162.54:597:31Waning Gibbous15Fri
16Sat1:045.32:365.17:340.18:012.44:597:31Waning Gibbous16Sat
17Sun1:484.93:095.38:080.58:532.25:007:30Waning Gibbous17Sun
18Mon2:394.53:455.58:450.99:541.95:017:30Third Quarter18Mon
19Tue3:434.14:265.79:281.411:011.55:027:29Third Quarter19Tue
20Wed5:073.85:125.910:192.05:027:28Third Quarter20Wed
21Thu6:433.76:046.212:091.011:20 AM2.45:037:28Third Quarter21Thu
22Fri8:103.96:596.41:130.512:272.75:047:27Waning Crescent22Fri
23Sat9:174.37:556.72:10-0.11:332.85:057:26Waning Crescent23Sat
24Sun10:114.68:517.03:03-0.62:352.75:067:26Waning Crescent24Sun
25Mon10:584.99:467.13:52-1.03:332.55:067:25New Moon25Mon
26Tue11:415.210:397.04:39-1.24:282.35:077:24New Moon26Tue
27Wed12:235.55:24-1.25:232.05:087:23New Moon27Wed
28Thu1:045.76:08-1.06:191.75:097:22Waxing Crescent28Thu
29Fri12:266.41:445.96:52-0.67:161.55:107:21Waxing Crescent29Fri
30Sat1:215.92:266.07:35-0.18:151.45:107:21Waxing Crescent30Sat
31Sun2:185.33:086.08:190.69:191.35:117:20Waxing Crescent31Sun
DateHigh TideLow TideSunMoonDate
AMftPMftAMftPMftRiseSet
Tidal Data Source: (9414792)

Common Questions About Alcatraz Island, CA Tides

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What time does the tide turn (slack tide) in Alcatraz Island, CA today?

Slack tide in Alcatraz Island, CA is approximately 5:40 am — midway between the next high and low tide, when tidal current is weakest. This is the preferred window for boat crossings, underwater visibility, and fishing in areas with strong currents.

Is this week a spring tide or neap tide in Alcatraz Island, CA?

Alcatraz Island, CA is currently in a transitional phase. Tonight's moon is 66% illuminated. Spring tides (largest swings) occur near new and full moons; neap tides (smallest swings) occur near first and third quarter moons. Tidal ranges this week are shifting between spring and neap.

What datum are Alcatraz Island, CA tide heights measured from?

Tide heights on this page are measured from Mean Lower Low Water (MLLW), the U.S. NOAA standard. A height of 0 ft represents the 19-year average of each day's lower low tide. Negative values indicate a "minus tide" — water levels below that long-term reference.

What factors can affect the tide predictions for Alcatraz Island, CA?

Tide predictions for Alcatraz Island, CA come from NOAA's harmonic analysis and are typically accurate within about ±10 minutes on timing and ±0.5 ft on height. Actual water levels can deviate further due to sustained winds, atmospheric pressure changes, river flow, and storm surge. During major weather events, be sure to check US Harbors weather pages for factors that could impact tidal predictions.

Which NOAA station provides tide data for Alcatraz Island, CA?

Tide data for Alcatraz Island, CA is sourced from NOAA Station #9414792. View the official NOAA station page at https://tidesandcurrents.noaa.gov/stationhome.html?id=9414792.

What is the moon phase in Alcatraz Island, CA tonight?

Tonight the moon over Alcatraz Island, CA is First Quarter (66% illuminated). This places Alcatraz Island, CA in a transitional tide cycle, so tidal ranges are shifting between spring and neap this week.

US Harbors Tidal Data

The data in our tide charts, tide tables, and tide graphs is provided by NOAA and others. These predictions are derived mathematically from numerous inputs, including data from historical tide stations and nearby locations where sensors are actively recording. As shown in the tide graph at the top of this page, “Predicted” tides (blue) are what forecasting models expect to happen. “Observed” tides (red) are those recorded by local sensors in real time, overlaid on the predictions for direct comparison. We display Observed water levels for a select group of harbors including Portland, Maine, where a physical sensor monitors water levels in real time.

LEARN MORE ABOUT OUR TIDE DATA