Tides Today & Tomorrow in Boston, MA

TIDE TIMES for Friday, August 21, 2026
The tide is currently falling in Boston, MA.

Next low tide (tomorrow) : in 3h 28m at 1:24 am (1.7 ft)
Next high tide (tomorrow) : 7:40 am (7.9 ft)
Sunset today : 7:36 pm
Sunrise tomorrow : 5:57 am
Moon phase : First Quarter (65% illuminated)
Tide Station Location : Station #8443970
Common Questions About Tides

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Boston, MA Tides - Oct 1924

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Nov 1924 >

Date		High Tide				Low Tide				Sun		Moon	Date
Date		AM	ft	PM	ft	AM	ft	PM	ft	Rise	Set	Moon	Date
1	Wed	12:19	10.8	12:38	11.4	6:29	-0.6	6:57	-1.0	5:40	5:26		1	Wed
2	Thu	1:07	10.7	1:25	11.4	7:16	-0.4	7:47	-0.9	5:42	5:24		2	Thu
3	Fri	1:58	10.4	2:16	11.2	8:05	-0.1	8:41	-0.7	5:43	5:22		3	Fri
4	Sat	2:53	10.1	3:11	11.0	8:59	0.2	9:39	-0.3	5:44	5:21		4	Sat
5	Sun	3:53	9.7	4:12	10.7	9:58	0.6	10:40	-0.1	5:45	5:19		5	Sun
6	Mon	4:58	9.5	5:17	10.4	11:01	0.8	11:44	0.1	5:46	5:17		6	Mon
7	Tue	6:04	9.4	6:23	10.3			12:05	0.9	5:47	5:15		7	Tue
8	Wed	7:10	9.6	7:29	10.3	12:47	0.2	1:10	0.8	5:48	5:14		8	Wed
9	Thu	8:11	9.8	8:31	10.4	1:49	0.1	2:12	0.6	5:49	5:12		9	Thu
10	Fri	9:05	10.2	9:25	10.5	2:45	0.0	3:08	0.2	5:50	5:10		10	Fri
11	Sat	9:53	10.4	10:14	10.5	3:35	-0.1	3:58	0.0	5:52	5:09		11	Sat
12	Sun	10:36	10.5	10:59	10.4	4:21	0.0	4:44	-0.2	5:53	5:07		12	Sun
13	Mon	11:16	10.6	11:42	10.2	5:03	0.1	5:28	-0.2	5:54	5:06		13	Mon
14	Tue	11:56	10.5			5:44	0.3	6:10	-0.1	5:55	5:04		14	Tue
15	Wed	12:23	9.9	12:35	10.3	6:24	0.6	6:52	0.1	5:56	5:02		15	Wed
16	Thu	1:05	9.6	1:14	10.1	7:04	1.0	7:34	0.4	5:57	5:01		16	Thu
17	Fri	1:47	9.3	1:56	9.8	7:46	1.3	8:18	0.7	5:59	4:59		17	Fri
18	Sat	2:31	8.9	2:40	9.5	8:30	1.7	9:04	1.0	6:00	4:58		18	Sat
19	Sun	3:19	8.6	3:28	9.3	9:17	2.0	9:54	1.3	6:01	4:56		19	Sun
20	Mon	4:11	8.4	4:21	9.1	10:09	2.2	10:47	1.4	6:02	4:54		20	Mon
21	Tue	5:04	8.4	5:15	9.0	11:03	2.2	11:40	1.4	6:03	4:53		21	Tue
22	Wed	5:58	8.5	6:10	9.1	11:58	2.1			6:05	4:51		22	Wed
23	Thu	6:50	8.8	7:05	9.3	12:32	1.3	12:52	1.7	6:06	4:50		23	Thu
24	Fri	7:40	9.2	7:57	9.6	1:23	1.0	1:45	1.2	6:07	4:48		24	Fri
25	Sat	8:27	9.8	8:47	10.0	2:13	0.6	2:36	0.6	6:08	4:47		25	Sat
26	Sun	9:11	10.4	9:34	10.4	2:59	0.2	3:24	-0.1	6:09	4:46		26	Sun
27	Mon	9:54	11.0	10:20	10.7	3:45	-0.2	4:11	-0.7	6:11	4:44		27	Mon
28	Tue	10:38	11.5	11:08	10.9	4:30	-0.5	4:59	-1.2	6:12	4:43		28	Tue
29	Wed	11:24	11.8	11:57	10.9	5:16	-0.7	5:47	-1.5	6:13	4:41		29	Wed
30	Thu			12:12	11.9	6:04	-0.7	6:37	-1.6	6:14	4:40		30	Thu
31	Fri	12:49	10.7	1:03	11.8	6:53	-0.5	7:29	-1.4	6:16	4:39		31	Fri
Date		High Tide				Low Tide				Sun		Moon	Date
Date		AM	ft	PM	ft	AM	ft	PM	ft	Rise	Set	Moon	Date

Tidal Data Source: (8443970)

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What time does the tide turn (slack tide) in Boston, MA today?

Slack tide in Boston, MA is approximately 4:32 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 Boston, MA?

Boston, MA is currently in a transitional phase. Tonight's moon is 65% 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 Boston, MA 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 Boston, MA?

Tide predictions for Boston, MA 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 Boston, MA?

Tide data for Boston, MA is sourced from NOAA Station #8443970. View the official NOAA station page at https://tidesandcurrents.noaa.gov/stationhome.html?id=8443970.

What is the moon phase in Boston, MA tonight?

Tonight the moon over Boston, MA is First Quarter (65% illuminated). This places Boston, MA 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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