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MA · NOAA 8443970 · 42° 21′ N · 71° 03′ W
Tides at Boston
A semidiurnal tide (form factor 0.16), spring this week. Predicted from the station's 34 harmonic constants; heights above mean lower low water, times in station time. Weather is not in these numbers.
This week
| When | Water | Height |
|---|---|---|
| Mon, Oct 26, 6:01 PM | Low | -0.9 ft |
| Tue, Oct 27, 12:10 AM | High | 10.2 ft |
| Tue, Oct 27, 6:13 AM | Low | 0.0 ft |
| Tue, Oct 27, 12:20 PM | High | 11.5 ft |
| Tue, Oct 27, 6:48 PM | Low | -1.1 ft |
| Wed, Oct 28, 12:58 AM | High | 10.1 ft |
| Wed, Oct 28, 6:59 AM | Low | 0.0 ft |
| Wed, Oct 28, 1:07 PM | High | 11.6 ft |
| Wed, Oct 28, 7:37 PM | Low | -1.1 ft |
| Thu, Oct 29, 1:48 AM | High | 10.0 ft |
| Thu, Oct 29, 7:48 AM | Low | 0.2 ft |
| Thu, Oct 29, 1:58 PM | High | 11.5 ft |
| Thu, Oct 29, 8:29 PM | Low | -0.9 ft |
| Fri, Oct 30, 2:41 AM | High | 9.7 ft |
| Fri, Oct 30, 8:40 AM | Low | 0.5 ft |
| Fri, Oct 30, 2:51 PM | High | 11.2 ft |
| Fri, Oct 30, 9:24 PM | Low | -0.5 ft |
| Sat, Oct 31, 3:38 AM | High | 9.4 ft |
| Sat, Oct 31, 9:37 AM | Low | 0.8 ft |
| Sat, Oct 31, 3:50 PM | High | 10.7 ft |
| Sat, Oct 31, 10:23 PM | Low | -0.1 ft |
| Sun, Nov 1, 3:40 AM | High | 9.2 ft |
| Sun, Nov 1, 9:39 AM | Low | 1.1 ft |
| Sun, Nov 1, 3:54 PM | High | 10.3 ft |
| Sun, Nov 1, 10:25 PM | Low | 0.2 ft |
| Mon, Nov 2, 4:47 AM | High | 9.1 ft |
| Mon, Nov 2, 10:45 AM | Low | 1.3 ft |
The constants that make it
| Constituent | Amplitude | Phase |
|---|---|---|
| M2 | 4.5 ft | 109.2° |
| N2 | 1.0 ft | 76.7° |
| S2 | 0.7 ft | 146.2° |
| K1 | 0.5 ft | 205.6° |
| O1 | 0.4 ft | 187.1° |
| L2 | 0.2 ft | 160.4° |
| NU2 | 0.2 ft | 84.0° |
| K2 | 0.2 ft | 146.1° |
The eight largest of 34. Source: NOAA CO-OPS harmonic constituents for 8443970, public domain.
The year as a print
The last two days, measured
At Mon, Oct 26 17:30 the gauge read -0.2 ft, 0.4 ft above the computed curve: wind and pressure, not the moon. The widest gap of the two days was 0.7 ft, at Sat, Oct 24 17:48.
- Computed here, from the constants
- NOAA's own prediction
- Measured at the gauge, every six minutes
The last twelve hours as numbers
| Station time | Measured | Computed here | NOAA |
|---|---|---|---|
| Mon, Oct 26 06:00 | 0.58 ft | 0.32 ft | 0.31 ft |
| Mon, Oct 26 07:00 | 2.46 ft | 1.89 ft | 1.89 ft |
| Mon, Oct 26 08:00 | 4.51 ft | 4.32 ft | 4.32 ft |
| Mon, Oct 26 09:00 | 7.03 ft | 6.96 ft | 6.96 ft |
| Mon, Oct 26 10:00 | 9.50 ft | 9.37 ft | 9.38 ft |
| Mon, Oct 26 11:00 | 11.01 ft | 10.93 ft | 10.94 ft |
| Mon, Oct 26 12:00 | 11.36 ft | 11.11 ft | 11.12 ft |
| Mon, Oct 26 13:00 | 10.15 ft | 9.92 ft | 9.94 ft |
| Mon, Oct 26 14:00 | 8.01 ft | 7.73 ft | 7.75 ft |
| Mon, Oct 26 15:00 | 5.62 ft | 5.00 ft | 5.02 ft |
| Mon, Oct 26 16:00 | 2.74 ft | 2.25 ft | 2.26 ft |
| Mon, Oct 26 17:00 | 0.48 ft | 0.04 ft | 0.05 ft |
Measured heights from NOAA CO-OPS station 8443970, preliminary, above mean lower low water. The print carries the computed curve only: one year, no weather.