Tides Today & Tomorrow in Boston, MA

TIDE TIMES for Friday, August 21, 2026
The tide is currently rising in Boston, MA.
Next low tide : 12:34 pm (2.3 ft)
Next high tide : in 4h 35m at 6:40 am (8.0 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

Boston, MA Tides - Jan 1927

DateHigh TideLow TideSunMoonDate
AMftPMftAMftPMftRiseSet
1Sat8:589.99:348.72:441.23:230.27:134:21Waning Crescent1Sat
2Sun9:4210.310:199.03:300.94:09-0.37:134:22New Moon2Sun
3Mon10:2610.711:059.24:150.64:54-0.77:134:23New Moon3Mon
4Tue11:1111.011:519.45:010.35:40-1.07:134:24New Moon4Tue
5Wed11:5911.25:480.06:27-1.27:134:25Waxing Crescent5Wed
6Thu12:399.612:4811.26:37-0.17:15-1.37:134:26Waxing Crescent6Thu
7Fri1:289.81:3911.17:28-0.28:04-1.27:134:27Waxing Crescent7Fri
8Sat2:199.92:3210.88:22-0.18:56-0.97:134:28Waxing Crescent8Sat
9Sun3:1210.03:3010.39:190.09:50-0.67:124:29First Quarter9Sun
10Mon4:0810.04:319.810:200.110:47-0.27:124:30First Quarter10Mon
11Tue5:0710.15:349.411:220.111:450.17:124:31First Quarter11Tue
12Wed6:0610.16:399.112:260.17:124:32Waxing Gibbous12Wed
13Thu7:0610.27:459.012:430.41:290.07:114:33Waxing Gibbous13Thu
14Fri8:0510.38:469.01:430.52:31-0.27:114:34Waxing Gibbous14Fri
15Sat9:0010.49:419.02:400.63:26-0.47:104:35Waxing Gibbous15Sat
16Sun9:5010.410:319.13:320.64:16-0.57:104:36Full Moon16Sun
17Mon10:3710.411:179.14:210.65:02-0.57:094:38Full Moon17Mon
18Tue11:2110.45:060.65:45-0.47:094:39Full Moon18Tue
19Wed12:009.012:0410.25:500.66:26-0.37:084:40Full Moon19Wed
20Thu12:419.012:4510.06:330.77:06-0.17:084:41Waning Gibbous20Thu
21Fri1:208.91:269.77:150.87:460.27:074:42Waning Gibbous21Fri
22Sat1:598.92:089.47:581.08:260.57:064:44Waning Gibbous22Sat
23Sun2:408.82:529.08:421.29:080.87:064:45Waning Gibbous23Sun
24Mon3:238.73:398.69:301.49:531.17:054:46Third Quarter24Mon
25Tue4:088.74:298.310:201.510:401.47:044:47Third Quarter25Tue
26Wed4:568.75:228.011:131.511:291.57:034:49Third Quarter26Wed
27Thu5:458.86:177.912:071.47:034:50Third Quarter27Thu
28Fri6:379.07:147.912:201.61:031.17:024:51Waning Crescent28Fri
29Sat7:309.38:118.11:141.51:590.77:014:53Waning Crescent29Sat
30Sun8:229.89:038.52:081.22:520.27:004:54Waning Crescent30Sun
31Mon9:1310.39:539.03:000.83:42-0.46:594:55New Moon31Mon
DateHigh TideLow TideSunMoonDate
AMftPMftAMftPMftRiseSet
Tidal Data Source: (8443970)

Common Questions About Boston, MA Tides

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

Slack tide in Boston, MA is approximately 9:37 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