Major Flood
8 ft
Current Water Level
Gage Height
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Streamflow
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Last Reading
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This is an NWS forecast point (LID: NTKM3). Live data may be limited. View on NWS AHPS →
FLOOD STAGES
Know the flood categories.
Flood stages defined by the National Weather Service. Gage height data from USGS Water Resources.
Moderate Flood
6.5 ft
Minor Flood
5 ft
Action Stage
4 ft
What Floods at Each Level
10 ft
This is a degree of flooding never experienced before. Life threatening flooding affects roads around Nantucket Harbor and in the Downtown Historic District with flooding more than 3 feet deep. Many road closures and some evacuations can be expected. Flooding also impacts the Atlantic Avenue area on the south side of the island. Large surf will also result in significant beach erosion and debris on coastal roads.
8 ft
This is a degree of flooding rarely seen. Life threatening flooding more than 3 feet deep affects many roads around Nantucket Harbor and in the Downtown Historic District. Road closures and some evacuations can be expected. Flooding also impacts the Atlantic Avenue area on the south side of the island. Large surf will also result in significant beach erosion and debris on coastal roads.
7 ft
Many roads near Nantucket Harbor and in the Downtown Historic District become impassable with 2 to 3 feet of water and affects access to the ferry terminals. Flooding affects Easy Street, South Beach Street, Easton Street, Walsh Street, Willard Street, and Straight Wharf.
6 ft
Many roads near Nantucket Harbor become impassable with 1 to 2 feet of water and affects access to the ferry terminals. This includes Easy Street, South Beach Street, Easton Street, Walsh Street, Willard Street, and Straight Wharf.
5 ft
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.
Impact statements from the National Weather Service, describing what typically happens at each water level.
7-Day Water Level Chart
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Historic Crests
| Date | Stage | Flow |
|---|---|---|
| Oct 29, 1991 | 7.87 ft | — |
| Jan 3, 2018 | 7.36 ft | — |
| Jan 26, 2015 | 7.21 ft | — |
About This Gauge
NWS LID
NTKM3
River
Nantucket Harbor
County
Nantucket, MA
Coordinates
41.2853°N, 70.0964°W
Get Flood Alerts for Nantucket Harbor
StormCast monitors this gauge and sends a push notification to your phone when the water level crosses into a new flood category — even at 3 AM.
Frequently Asked Questions
What is the current water level of Nantucket Harbor at Nantucket (IN MLLW)?
The Nantucket Harbor at Nantucket (IN MLLW) gauge is maintained by USGS and reports water levels every 15 minutes. Visit this page to see the latest reading updated live, or download StormCast to get push alerts when levels rise.
What is flood stage for Nantucket Harbor at Nantucket (IN MLLW)?
The NWS-defined flood stage for Nantucket Harbor at Nantucket (IN MLLW) is 5 feet. Action stage begins at 4 feet. Moderate flooding starts at 6.5 feet, and major flooding at 8 feet.
How do I get alerts when Nantucket Harbor rises?
Download StormCast free on Google Play, go to River Gauges, and add Nantucket Harbor at Nantucket (IN MLLW) to your watchlist. StormCast will send a push notification to your phone whenever the water level crosses into a new NWS flood category.
Where is the Nantucket Harbor at Nantucket (IN MLLW) gauge located?
The gauge is located in Nantucket County, Massachusetts at coordinates 41.2853°N, 70.0964°W. Data is provided by the U.S. Geological Survey and the National Weather Service.
More Resources
Source & Notes
Data provided by: NOAA National Ocean Service
- <span style="color: #ff0000;">Please refer to our <span style="background-color: #ffff00;"><a style="color: #ff0000; background-color: #ffff00;" title="Link to CFWBOX" href="https://forecast.weather.gov/product.php?site=NWS&issuedby=BOX&product=CFW&format=CI&version=1&glossary=0">Coastal Hazard Message</a></span> for specific information regarding Coastal Flood Watches, Warnings and Advisories. Actual impacts from any coastal flooding event may vary due to factors such as rainfall, wave action, and the number of tide cycles during which there is an onshore flow. During tropical cyclones, please refer <span style="background-color: #ffff00;"><a style="background-color: #ffff00;" title="Link to TCVBOX" href="https://forecast.weather.gov/product.php?site=NWS&issuedby=BOX&product=TCV&format=CI&version=1&glossary=1">here</a></span> for additional storm surge information.</span>
- <span style="color: #ff0000;">During a Tropical Storm or Hurricane Watch or Warning, inundation mapping provided by the <span style="background-color: #ffff00;"><a style="color: #ff0000; background-color: #ffff00;" href="https://www.nhc.noaa.gov">National Hurricane Center</a></span> (go to the web site and select the storm of interest) reflects a reasonable worst case scenario. The forecast above is the total water forecast that is most likely to occur.</span>