Tides Today & Tomorrow in Alcatraz Island, CA

TIDE TIMES for Friday, August 21, 2026
The tide is currently rising in Alcatraz Island, CA.

Next low tide : 1:22 pm (3.6 ft)
Next high tide : in 2h 57m at 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 - Feb 1938

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Date		High Tide				Low Tide				Sun		Moon	Date
Date		AM	ft	PM	ft	AM	ft	PM	ft	Rise	Set	Moon	Date
1	Tue	12:39	5.0	11:46 AM	5.8	5:47	2.2	6:14	-0.2	7:14	5:32		1	Tue
2	Wed	1:06	5.2	12:26	5.5	6:24	2.0	6:44	0.0	7:13	5:33		2	Wed
3	Thu	1:35	5.3	1:08	5.2	7:05	1.8	7:16	0.4	7:12	5:34		3	Thu
4	Fri	2:06	5.5	1:56	4.8	7:51	1.6	7:52	0.8	7:11	5:36		4	Fri
5	Sat	2:40	5.6	2:54	4.4	8:44	1.3	8:32	1.4	7:10	5:37		5	Sat
6	Sun	3:20	5.8	4:09	3.9	9:46	1.1	9:19	1.9	7:09	5:38		6	Sun
7	Mon	4:07	5.9	5:44	3.7	10:57	0.8	10:19	2.4	7:08	5:39		7	Mon
8	Tue	5:03	6.0	7:21	3.9			12:13	0.4	7:07	5:40		8	Tue
9	Wed	6:06	6.1	8:36	4.2			1:22	0.0	7:06	5:41		9	Wed
10	Thu	7:12	6.3	9:32	4.6	12:54	2.8	2:22	-0.4	7:05	5:42		10	Thu
11	Fri	8:14	6.5	10:18	4.9	2:04	2.7	3:15	-0.8	7:04	5:43		11	Fri
12	Sat	9:13	6.6	10:59	5.2	3:05	2.3	4:02	-0.9	7:03	5:44		12	Sat
13	Sun	10:07	6.6	11:37	5.5	3:59	2.0	4:45	-0.9	7:02	5:46		13	Sun
14	Mon	10:59	6.5			4:51	1.6	5:26	-0.8	7:00	5:47		14	Mon
15	Tue	12:15	5.7	11:50 AM	6.2	5:41	1.3	6:06	-0.4	6:59	5:48		15	Tue
16	Wed	12:51	5.8	12:40	5.7	6:30	1.0	6:45	0.1	6:58	5:49		16	Wed
17	Thu	1:27	5.9	1:30	5.3	7:19	0.9	7:23	0.6	6:57	5:50		17	Thu
18	Fri	2:03	5.8	2:24	4.7	8:10	0.9	8:03	1.2	6:56	5:51		18	Fri
19	Sat	2:40	5.7	3:25	4.2	9:05	0.9	8:46	1.8	6:54	5:52		19	Sat
20	Sun	3:21	5.6	4:40	3.9	10:06	1.0	9:38	2.4	6:53	5:53		20	Sun
21	Mon	4:07	5.4	6:14	3.7	11:14	1.0	10:45	2.8	6:52	5:54		21	Mon
22	Tue	5:01	5.3	7:45	3.8			12:24	0.9	6:51	5:55		22	Tue
23	Wed	6:01	5.2	8:48	4.1	12:05	3.0	1:27	0.7	6:49	5:56		23	Wed
24	Thu	7:02	5.3	9:31	4.3	1:16	3.0	2:19	0.5	6:48	5:57		24	Thu
25	Fri	7:58	5.4	10:04	4.5	2:13	2.8	3:02	0.3	6:47	5:58		25	Fri
26	Sat	8:47	5.5	10:32	4.6	2:59	2.6	3:39	0.1	6:45	5:59		26	Sat
27	Sun	9:32	5.6	10:59	4.8	3:39	2.3	4:11	0.0	6:44	6:00		27	Sun
28	Mon	10:14	5.6	11:24	5.0	4:15	2.0	4:42	0.0	6:42	6:01		28	Mon
Date		High Tide				Low Tide				Sun		Moon	Date
Date		AM	ft	PM	ft	AM	ft	PM	ft	Rise	Set	Moon	Date

Tidal Data Source: (9414792)

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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 11:27 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

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