Coastal Flood Warnings/Watches/Statements
Issued by NWS Boston, MA
Issued by NWS Boston, MA
229
WHUS41 KBOX 210613
CFWBOX
Coastal Hazard Message
National Weather Service Boston/Norton MA
213 AM EDT Thu Aug 21 2025
MAZ023-024-211930-
/O.CON.KBOX.SU.Y.0001.000000T0000Z-250824T0000Z/
/O.CON.KBOX.CF.Y.0005.250822T0200Z-250822T0600Z/
/O.CON.KBOX.CF.Y.0004.250823T0200Z-250823T0600Z/
Dukes MA-Nantucket MA-
213 AM EDT Thu Aug 21 2025
...HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 8 PM EDT SATURDAY...
...COASTAL FLOOD ADVISORY REMAINS IN EFFECT FROM 10 PM THIS
EVENING TO 2 AM EDT FRIDAY...
...COASTAL FLOOD ADVISORY REMAINS IN EFFECT FROM 10 PM FRIDAY TO
2 AM EDT SATURDAY...
* WHAT...For the High Surf Advisory, large breaking waves of 6
to 20 feet in the surf zone. For the first Coastal Flood
Advisory, up to one half foot of inundation above ground level
expected in low-lying areas near shorelines and tidal
waterways (3.5 to 5.4 feet Mean Lower Low Water). For the
second Coastal Flood Advisory, up to one half foot of
inundation above ground level expected in low-lying areas near
shorelines and tidal waterways (3.4 to 5.1 feet Mean Lower Low
Water).
* WHERE...Dukes and Nantucket MA Counties.
* WHEN...For the High Surf Advisory, until 8 PM EDT Saturday.
For the first Coastal Flood Advisory, from 10 PM this evening
to 2 AM EDT Friday. For the second Coastal Flood Advisory,
from 10 PM Friday to 2 AM EDT Saturday.
* IMPACTS...Roads remain passable. Low lying areas and roads
near Nantucket Harbor, including Easy Street, may experience
pockets of shallow flooding less than one foot deep. Dangerous
swimming and surfing conditions and localized beach erosion.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If travel is required, allow extra time as some roads may be
closed. Do not drive around barricades or through water of
unknown depth. Take the necessary actions to protect flood-prone
property.
Inexperienced swimmers should remain out of the water due to
dangerous surf conditions.
&&
&&
Time of high total tides are approximate to the nearest hour.
Edgartown
MLLW Categories - Minor 4.0 ft, Moderate 5.0 ft, Major 7.0 ft
MHHW Categories - Minor 1.3 ft, Moderate 2.3 ft, Major 4.3 ft
Total Total Departure
Day/Time Tide Tide from Norm Waves Flood
ft MLLW ft MHHW ft ft Impact
-------- --------- --------- --------- ------- --------
21/11 AM 2.7/ 3.2 0.0/ 0.5 0.6/ 1.1 5-6 None
21/11 PM 4.2/ 4.7 1.5/ 2.0 1.3/ 1.8 7-8 Minor
22/12 PM 3.6/ 4.1 0.9/ 1.4 1.5/ 2.0 6-7 None
23/12 AM 3.7/ 4.2 1.1/ 1.6 1.1/ 1.6 4 Minor
23/01 PM 2.7/ 3.2 0.0/ 0.5 0.6/ 1.1 3 None
Vineyard Haven
MLLW Categories - Minor 4.5 ft, Moderate 6.0 ft, Major 7.0 ft
MHHW Categories - Minor 2.5 ft, Moderate 4.0 ft, Major 5.0 ft
Total Total Departure
Day/Time Tide Tide from Norm Waves Flood
ft MLLW ft MHHW ft ft Impact
-------- --------- --------- --------- ------- --------
21/10 AM 2.2/ 2.7 0.2/ 0.8 0.6/ 1.1 4 None
21/11 PM 3.2/ 3.7 1.3/ 1.8 1.2/ 1.7 5-6 None
22/12 PM 3.2/ 3.7 1.2/ 1.7 1.4/ 1.9 5 None
22/11 PM 3.2/ 3.7 1.2/ 1.7 1.2/ 1.7 3 None
23/12 PM 2.5/ 3.0 0.5/ 1.0 0.7/ 1.1 2-3 None
23/11 PM 2.3/ 2.8 0.4/ 0.9 0.7/ 1.1 2 None
Nantucket Harbor
MLLW Categories - Minor 5.0 ft, Moderate 6.5 ft, Major 8.0 ft
MHHW Categories - Minor 1.4 ft, Moderate 2.9 ft, Major 4.4 ft
Total Total Departure
Day/Time Tide Tide from Norm Waves Flood
ft MLLW ft MHHW ft ft Impact
-------- --------- --------- --------- ------- --------
21/11 AM 3.4/ 3.9 -0.2/ 0.2 0.5/ 1.0 6-7 None
22/12 AM 5.2/ 5.7 1.6/ 2.0 1.2/ 1.7 9-10 Minor
22/12 PM 4.5/ 5.0 0.9/ 1.4 1.5/ 2.0 8-9 None
23/12 AM 4.9/ 5.4 1.3/ 1.8 1.1/ 1.6 7 Minor
23/01 PM 3.7/ 4.2 0.1/ 0.6 0.6/ 1.1 5 None
&&
$$
MAZ020-RIZ006-007-211930-
/O.CON.KBOX.SU.Y.0001.000000T0000Z-250824T0000Z/
Southern Bristol MA-Washington RI-Newport RI-
213 AM EDT Thu Aug 21 2025
...HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 8 PM EDT SATURDAY...
* WHAT...Large breaking waves of 5 to 19 feet in the surf zone.
* WHERE...In Massachusetts, Southern Bristol County. In Rhode
Island, Washington and Newport Counties.
* WHEN...Until 8 PM EDT Saturday.
* IMPACTS...Dangerous swimming and surfing conditions and
localized beach erosion.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Inexperienced swimmers should remain out of the water due to
dangerous surf conditions.
&&
$$
MAZ021-022-211930-
/O.CON.KBOX.SU.Y.0001.000000T0000Z-250824T0000Z/
Southern Plymouth MA-Barnstable MA-
213 AM EDT Thu Aug 21 2025
...HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 8 PM EDT SATURDAY...
* WHAT...Large breaking waves of 4 to 18 feet in the surf zone.
* WHERE...Southern Plymouth and Barnstable MA Counties.
* WHEN...Until 8 PM EDT Saturday.
* IMPACTS...Dangerous swimming and surfing conditions and
localized beach erosion.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Inexperienced swimmers should remain out of the water due to
dangerous surf conditions.
&&
$$
RIZ008-211930-
/O.CON.KBOX.SU.Y.0001.000000T0000Z-250824T0000Z/
Block Island RI-
213 AM EDT Thu Aug 21 2025
...HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 8 PM EDT SATURDAY...
* WHAT...Large breaking waves of 5 to 20 feet in the surf zone.
* WHERE...Block Island RI.
* WHEN...Until 8 PM EDT Saturday.
* IMPACTS...Dangerous swimming and surfing conditions and
localized beach erosion.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Inexperienced swimmers should remain out of the water due to
dangerous surf conditions.
&&
$$
MAZ007-019-211930-
/O.CON.KBOX.SU.Y.0001.250821T1800Z-250824T0000Z/
Eastern Essex MA-Eastern Plymouth MA-
213 AM EDT Thu Aug 21 2025
...HIGH SURF ADVISORY REMAINS IN EFFECT FROM 2 PM THIS AFTERNOON
TO 8 PM EDT SATURDAY...
* WHAT...Large breaking waves of 4 to 12 feet expected in the
surf zone.
* WHERE...Eastern Essex and Eastern Plymouth MA Counties.
* WHEN...From 2 PM this afternoon to 8 PM EDT Saturday.
* IMPACTS...Dangerous swimming and surfing conditions and
localized beach erosion.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Inexperienced swimmers should remain out of the water due to
dangerous surf conditions.
&&
$$