Minus tides at Groton
The lowest predicted waters at Groton, through 2030. The days each year when the sea goes furthest out.
What a minus tide is
Tide heights are measured from a datum — here MLLW — which is roughly the average of the lower low waters. Most low tides sit a little above it. A few times a year one falls below, and the height is printed as a negative number: a minus tide.
They happen on the same days as the king tides, and for the same reason. When the sun and moon pull together the water comes up further than usual, and it also goes out further than usual. The big high and the big low are six hours apart on the same day.
A foot below datum does not sound like much. On a shallow shore it can mean a few hundred yards of ground uncovered that nobody sees the rest of the year.
What to do at low water at Groton
The smallest range on the Sound, but the strongest current — the water through The Race and Fishers Island Sound moves hard, and it is the current rather than the height that governs anything afloat.
Low water uncovers the flats in the Mystic and Pawcatuck rivers and around Napatree. Shellfishing is town-managed; check the current openings.
Minus tides still to come
22–26 December 2026
| Date | Low water | Height |
|---|---|---|
| 22 DecTue | 1:01 am | 0.0 ft |
| 22 DecTue | 2:08 pm | -0.4 ft |
| 23 DecWed | 1:55 am | -0.2 ft |
| 23 DecWed | 2:58 pm | -0.5 ft |
| 24 DecThu | 2:49 am | -0.3 ft |
| 24 DecThu | 3:47 pm | -0.6 ft |
| 25 DecFri | 3:43 am | -0.4 ft |
| 25 DecFri | 4:37 pm | -0.6 ft |
| 26 DecSat | 4:37 am | -0.3 ft |
| 26 DecSat | 5:29 pm | -0.5 ft |
21–25 January 2027
| Date | Low water | Height |
|---|---|---|
| 21 JanThu | 1:43 am | -0.3 ft |
| 21 JanThu | 2:39 pm | -0.6 ft |
| 22 JanFri | 2:39 am | -0.5 ft |
| 22 JanFri | 3:28 pm | -0.7 ft |
| 23 JanSat | 3:32 am | -0.6 ft |
| 23 JanSat | 4:15 pm | -0.7 ft |
| 24 JanSun | 4:26 am | -0.5 ft |
| 24 JanSun | 5:03 pm | -0.6 ft |
| 25 JanMon | 5:22 am | -0.4 ft |
| 25 JanMon | 5:53 pm | -0.5 ft |
19–23 February 2027
| Date | Low water | Height |
|---|---|---|
| 19 FebFri | 1:33 am | -0.4 ft |
| 19 FebFri | 2:18 pm | -0.5 ft |
| 20 FebSat | 2:29 am | -0.5 ft |
| 20 FebSat | 3:06 pm | -0.6 ft |
| 21 FebSun | 3:21 am | -0.6 ft |
| 21 FebSun | 3:51 pm | -0.6 ft |
| 22 FebMon | 4:12 am | -0.6 ft |
| 22 FebMon | 4:35 pm | -0.5 ft |
| 23 FebTue | 5:04 am | -0.5 ft |
| 23 FebTue | 5:21 pm | -0.4 ft |
20–24 March 2027
| Date | Low water | Height |
|---|---|---|
| 20 MarSat | 2:24 am | -0.2 ft |
| 20 MarSat | 2:54 pm | -0.3 ft |
| 21 MarSun | 3:18 am | -0.4 ft |
| 21 MarSun | 3:41 pm | -0.3 ft |
| 22 MarMon | 4:09 am | -0.4 ft |
| 22 MarMon | 4:24 pm | -0.3 ft |
| 23 MarTue | 4:57 am | -0.4 ft |
| 23 MarTue | 5:07 pm | -0.2 ft |
| 24 MarWed | 5:45 am | -0.4 ft |
| 24 MarWed | 5:51 pm | 0.0 ft |
11–15 January 2028
| Date | Low water | Height |
|---|---|---|
| 11 JanTue | 2:03 am | -0.2 ft |
| 11 JanTue | 2:59 pm | -0.5 ft |
| 12 JanWed | 2:55 am | -0.4 ft |
| 12 JanWed | 3:45 pm | -0.6 ft |
| 13 JanThu | 3:46 am | -0.5 ft |
| 13 JanThu | 4:32 pm | -0.7 ft |
| 14 JanFri | 4:40 am | -0.5 ft |
| 14 JanFri | 5:21 pm | -0.6 ft |
| 15 JanSat | 5:38 am | -0.4 ft |
| 15 JanSat | 6:12 pm | -0.6 ft |
9–13 February 2028
| Date | Low water | Height |
|---|---|---|
| 9 FebWed | 1:47 am | -0.4 ft |
| 9 FebWed | 2:35 pm | -0.6 ft |
| 10 FebThu | 2:41 am | -0.6 ft |
| 10 FebThu | 3:21 pm | -0.7 ft |
| 11 FebFri | 3:33 am | -0.7 ft |
| 11 FebFri | 4:07 pm | -0.7 ft |
| 12 FebSat | 4:26 am | -0.7 ft |
| 12 FebSat | 4:53 pm | -0.7 ft |
| 13 FebSun | 5:22 am | -0.6 ft |
| 13 FebSun | 5:43 pm | -0.6 ft |
10–14 March 2028
| Date | Low water | Height |
|---|---|---|
| 10 MarFri | 2:28 am | -0.6 ft |
| 10 MarFri | 2:55 pm | -0.6 ft |
| 11 MarSat | 3:20 am | -0.7 ft |
| 11 MarSat | 3:40 pm | -0.6 ft |
| 12 MarSun | 5:12 am | -0.7 ft |
| 12 MarSun | 5:26 pm | -0.5 ft |
| 13 MarMon | 6:04 am | -0.6 ft |
| 13 MarMon | 6:15 pm | -0.3 ft |
| 14 MarTue | 7:00 am | -0.4 ft |
| 14 MarTue | 7:08 pm | -0.1 ft |
29 January – 2 February 2029
| Date | Low water | Height |
|---|---|---|
| 29 JanMon | 2:14 am | -0.2 ft |
| 29 JanMon | 3:00 pm | -0.5 ft |
| 30 JanTue | 3:02 am | -0.4 ft |
| 30 JanTue | 3:43 pm | -0.6 ft |
| 31 JanWed | 3:51 am | -0.5 ft |
| 31 JanWed | 4:26 pm | -0.6 ft |
| 1 FebThu | 4:42 am | -0.5 ft |
| 1 FebThu | 5:12 pm | -0.6 ft |
| 2 FebFri | 5:37 am | -0.5 ft |
| 2 FebFri | 6:01 pm | -0.5 ft |
28 February – 4 March 2029
| Date | Low water | Height |
|---|---|---|
| 28 FebWed | 2:45 am | -0.5 ft |
| 28 FebWed | 3:14 pm | -0.6 ft |
| 1 MarThu | 3:35 am | -0.6 ft |
| 1 MarThu | 3:58 pm | -0.6 ft |
| 2 MarFri | 4:26 am | -0.7 ft |
| 2 MarFri | 4:43 pm | -0.5 ft |
| 3 MarSat | 5:20 am | -0.6 ft |
| 3 MarSat | 5:33 pm | -0.4 ft |
| 4 MarSun | 6:18 am | -0.5 ft |
| 4 MarSun | 6:28 pm | -0.3 ft |
29 March – 2 April 2029
| Date | Low water | Height |
|---|---|---|
| 29 MarThu | 3:28 am | -0.5 ft |
| 29 MarThu | 3:44 pm | -0.4 ft |
| 30 MarFri | 4:20 am | -0.6 ft |
| 30 MarFri | 4:31 pm | -0.4 ft |
| 31 MarSat | 5:11 am | -0.7 ft |
| 31 MarSat | 5:18 pm | -0.3 ft |
| 1 AprSun | 6:03 am | -0.6 ft |
| 1 AprSun | 6:10 pm | -0.2 ft |
| 2 AprMon | 6:59 am | -0.4 ft |
| 2 AprMon | 7:07 pm | 0.0 ft |
2–6 January 2030
| Date | Low water | Height |
|---|---|---|
| 2 JanWed | 1:13 am | -0.3 ft |
| 2 JanWed | 2:06 pm | -0.5 ft |
| 3 JanThu | 2:08 am | -0.4 ft |
| 3 JanThu | 2:56 pm | -0.6 ft |
| 4 JanFri | 3:01 am | -0.4 ft |
| 4 JanFri | 3:44 pm | -0.6 ft |
| 5 JanSat | 3:52 am | -0.4 ft |
| 5 JanSat | 4:31 pm | -0.5 ft |
| 6 JanSun | 4:43 am | -0.3 ft |
| 6 JanSun | 5:18 pm | -0.4 ft |
19–23 March 2030
| Date | Low water | Height |
|---|---|---|
| 19 MarTue | 3:52 am | -0.4 ft |
| 19 MarTue | 4:09 pm | -0.3 ft |
| 20 MarWed | 4:39 am | -0.5 ft |
| 20 MarWed | 4:51 pm | -0.3 ft |
| 21 MarThu | 5:28 am | -0.5 ft |
| 21 MarThu | 5:37 pm | -0.3 ft |
| 22 MarFri | 6:20 am | -0.5 ft |
| 22 MarFri | 6:27 pm | -0.2 ft |
| 23 MarSat | 7:16 am | -0.4 ft |
| 23 MarSat | 7:24 pm | -0.1 ft |
23–27 December 2030
| Date | Low water | Height |
|---|---|---|
| 23 DecMon | 1:24 am | -0.3 ft |
| 23 DecMon | 2:19 pm | -0.5 ft |
| 24 DecTue | 2:19 am | -0.4 ft |
| 24 DecTue | 3:10 pm | -0.6 ft |
| 25 DecWed | 3:12 am | -0.5 ft |
| 25 DecWed | 3:59 pm | -0.7 ft |
| 26 DecThu | 4:06 am | -0.5 ft |
| 26 DecThu | 4:49 pm | -0.6 ft |
| 27 DecFri | 5:01 am | -0.4 ft |
| 27 DecFri | 5:41 pm | -0.5 ft |
Minus tides already past
1–5 January 2026
| Date | Low water | Height |
|---|---|---|
| 1 JanThu | 12:45 am | -0.1 ft |
| 1 JanThu | 1:50 pm | -0.5 ft |
| 2 JanFri | 1:43 am | -0.2 ft |
| 2 JanFri | 2:43 pm | -0.6 ft |
| 3 JanSat | 2:38 am | -0.3 ft |
| 3 JanSat | 3:32 pm | -0.6 ft |
| 4 JanSun | 3:31 am | -0.3 ft |
| 4 JanSun | 4:21 pm | -0.6 ft |
| 5 JanMon | 4:24 am | -0.3 ft |
| 5 JanMon | 5:10 pm | -0.5 ft |
30 January – 3 February 2026
| Date | Low water | Height |
|---|---|---|
| 30 JanFri | 12:36 am | -0.1 ft |
| 30 JanFri | 1:35 pm | -0.4 ft |
| 31 JanSat | 1:35 am | -0.3 ft |
| 31 JanSat | 2:26 pm | -0.5 ft |
| 1 FebSun | 2:30 am | -0.4 ft |
| 1 FebSun | 3:14 pm | -0.5 ft |
| 2 FebMon | 3:21 am | -0.4 ft |
| 2 FebMon | 3:59 pm | -0.5 ft |
| 3 FebTue | 4:10 am | -0.4 ft |
| 3 FebTue | 4:43 pm | -0.5 ft |
Going out safely
The water comes back. Work out when the tide turns before you walk out to anything, and allow more time than the return trip took — a rising tide fills channels behind you before it reaches where you are standing.
Wet rock is slippery, and what is exposed at a minus tide has been underwater long enough to be covered in weed. Anything living out there is usually protected by state or local rules; look it up before taking any of it home.