Tides Today & Tomorrow in Boston, MA

TIDE TIMES for Tuesday, July 21, 2026
The tide is currently falling in Boston, MA.

Next low tide (tomorrow) : in 5h 01m at 12:07 am (1.1 ft)
Next high tide (tomorrow) : 6:21 am (8.7 ft)
Sunset today : 8:14 pm
Sunrise tomorrow : 5:26 am
Moon phase : First Quarter (52% illuminated)
Tide Station Location : Station #8443970
Common Questions About Tides

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Boston, MA Tides - Jul 1979

< Jun 1979

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Aug 1979 >

Date		High Tide				Low Tide				Sun		Moon	Date
Date		AM	ft	PM	ft	AM	ft	PM	ft	Rise	Set	Moon	Date
1	Sun	4:33	9.3	5:08	9.2	10:50	1.0	11:15	1.7	5:10	8:24		1	Sun
2	Mon	5:22	9.0	5:54	9.2	11:37	1.2			5:11	8:24		2	Mon
3	Tue	6:13	8.8	6:42	9.4	12:06	1.7	12:25	1.3	5:11	8:24		3	Tue
4	Wed	7:05	8.7	7:30	9.6	12:58	1.5	1:14	1.4	5:12	8:24		4	Wed
5	Thu	7:59	8.7	8:20	9.9	1:50	1.3	2:05	1.3	5:12	8:23		5	Thu
6	Fri	8:53	8.9	9:10	10.3	2:44	0.9	2:56	1.1	5:13	8:23		6	Fri
7	Sat	9:46	9.2	9:59	10.8	3:36	0.3	3:48	0.8	5:14	8:23		7	Sat
8	Sun	10:36	9.5	10:48	11.3	4:27	-0.2	4:38	0.4	5:14	8:22		8	Sun
9	Mon	11:26	9.9	11:38	11.6	5:17	-0.7	5:28	0.0	5:15	8:22		9	Mon
10	Tue			12:17	10.2	6:06	-1.1	6:19	-0.3	5:16	8:22		10	Tue
11	Wed	12:30	11.8	1:09	10.5	6:56	-1.4	7:12	-0.5	5:17	8:21		11	Wed
12	Thu	1:22	11.9	2:01	10.7	7:47	-1.5	8:05	-0.5	5:17	8:21		12	Thu
13	Fri	2:16	11.7	2:54	10.9	8:38	-1.4	8:59	-0.5	5:18	8:20		13	Fri
14	Sat	3:11	11.4	3:48	10.9	9:30	-1.1	9:56	-0.3	5:19	8:20		14	Sat
15	Sun	4:08	10.9	4:45	10.8	10:25	-0.7	10:56	-0.1	5:20	8:19		15	Sun
16	Mon	5:09	10.4	5:43	10.7	11:21	-0.2	11:57	0.2	5:20	8:18		16	Mon
17	Tue	6:11	9.9	6:42	10.5			12:19	0.2	5:21	8:18		17	Tue
18	Wed	7:14	9.5	7:41	10.4	12:59	0.3	1:17	0.6	5:22	8:17		18	Wed
19	Thu	8:18	9.3	8:40	10.4	2:02	0.4	2:15	0.9	5:23	8:16		19	Thu
20	Fri	9:20	9.2	9:36	10.4	3:03	0.4	3:13	1.0	5:24	8:15		20	Fri
21	Sat	10:15	9.2	10:26	10.4	3:59	0.3	4:06	1.1	5:25	8:15		21	Sat
22	Sun	11:03	9.2	11:11	10.4	4:49	0.2	4:54	1.0	5:26	8:14		22	Sun
23	Mon	11:48	9.3	11:53	10.4	5:33	0.1	5:38	1.0	5:27	8:13		23	Mon
24	Tue			12:29	9.3	6:14	0.1	6:20	1.0	5:28	8:12		24	Tue
25	Wed	12:34	10.3	1:08	9.4	6:54	0.2	7:02	1.0	5:29	8:11		25	Wed
26	Thu	1:14	10.2	1:47	9.4	7:32	0.2	7:43	1.0	5:30	8:10		26	Thu
27	Fri	1:54	10.0	2:25	9.4	8:10	0.4	8:24	1.1	5:31	8:09		27	Fri
28	Sat	2:34	9.8	3:03	9.4	8:49	0.5	9:06	1.2	5:32	8:08		28	Sat
29	Sun	3:15	9.6	3:43	9.4	9:29	0.7	9:50	1.3	5:33	8:07		29	Sun
30	Mon	3:58	9.3	4:25	9.4	10:11	0.9	10:37	1.4	5:34	8:06		30	Mon
31	Tue	4:44	9.1	5:10	9.4	10:56	1.2	11:26	1.4	5:35	8:05		31	Tue
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 3:14 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 neap phase. Tonight's moon is 52% 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 near their weekly minimum.

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 (52% illuminated). This places Boston, MA in a neap tide cycle, so tidal ranges are near their weekly minimum 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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