Tides Today & Tomorrow in Boston, MA

TIDE TIMES for Friday, August 21, 2026
The tide is currently falling in Boston, MA.
Next low tide : in 40m at 12:34 pm (2.3 ft)
Next high tide : 6:53 pm (9.1 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 - Dec 1925

DateHigh TideLow TideSunMoonDate
AMftPMftAMftPMftRiseSet
1Tue11:3410.65:220.65:57-0.46:534:12Full Moon1Tue
2Wed12:119.412:1510.46:040.86:39-0.26:544:12Waning Gibbous2Wed
3Thu12:549.212:5610.16:461.07:210.16:554:12Waning Gibbous3Thu
4Fri1:369.01:399.97:291.38:030.46:564:12Waning Gibbous4Fri
5Sat2:198.82:239.58:131.68:480.76:574:11Waning Gibbous5Sat
6Sun3:058.63:109.29:011.89:350.96:584:11Third Quarter6Sun
7Mon3:538.54:019.09:521.910:241.16:594:11Third Quarter7Mon
8Tue4:438.64:548.810:451.911:131.27:004:11Third Quarter8Tue
9Wed5:328.75:478.711:381.87:014:11Third Quarter9Wed
10Thu6:219.06:418.712:031.212:311.57:024:11Waning Crescent10Thu
11Fri7:109.37:348.912:521.11:241.07:024:11Waning Crescent11Fri
12Sat7:579.88:259.21:420.92:160.57:034:11Waning Crescent12Sat
13Sun8:4310.49:159.52:300.63:06-0.17:044:11Waning Crescent13Sun
14Mon9:2910.910:029.73:180.23:54-0.77:054:12New Moon14Mon
15Tue10:1411.410:5110.04:05-0.14:42-1.27:054:12New Moon15Tue
16Wed11:0211.711:4110.14:53-0.35:31-1.57:064:12New Moon16Wed
17Thu11:5211.85:43-0.56:21-1.77:074:12Waxing Crescent17Thu
18Fri12:3310.212:4411.76:34-0.57:12-1.67:084:13Waxing Crescent18Fri
19Sat1:2610.21:3811.47:27-0.48:05-1.47:084:13Waxing Crescent19Sat
20Sun2:2110.12:3511.08:23-0.19:00-1.07:094:13Waxing Crescent20Sun
21Mon3:1810.03:3510.59:220.19:57-0.67:094:14First Quarter21Mon
22Tue4:199.94:3910.010:250.410:57-0.27:104:14First Quarter22Tue
23Wed5:219.95:459.611:300.511:560.27:104:15First Quarter23Wed
24Thu6:219.96:509.312:340.47:114:16Waxing Gibbous24Thu
25Fri7:2110.07:549.112:550.41:370.37:114:16Waxing Gibbous25Fri
26Sat8:1710.18:529.11:530.62:360.17:114:17Waxing Gibbous26Sat
27Sun9:0710.29:439.12:460.73:28-0.17:124:17Waxing Gibbous27Sun
28Mon9:5210.310:289.13:340.74:15-0.27:124:18Full Moon28Mon
29Tue10:3410.311:119.14:180.74:57-0.37:124:19Full Moon29Tue
30Wed11:1410.311:519.05:000.85:37-0.27:124:20Full Moon30Wed
31Thu11:5410.25:410.86:16-0.27:134:20Full Moon31Thu
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 3:43 pm — 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