Major Flood
15 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: BHBM3). 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
14 ft
Minor Flood
12.5 ft
Action Stage
11.5 ft
What Floods at Each Level
16 ft
This is a degree of flooding that has never been experienced before. Life threatening flooding more than 3 feet deep affects homes and roads from Revere and Winthrop through Hull, Quincy, Braintree, and Weymouth. In Boston, deep flooding affects the Seaport District including Atlantic Avenue, Long Wharf, and the Aquarium MBTA Station. Flooding will occur several hours before and after high tide. Follow the instructions of local officials and evacuate if asked to do so. Find alternate travel routes.
15 ft
This is a degree of flooding rarely seen. Life threatening flooding more than 3 feet deep affects many coastal roads and homes in low lying areas in Revere, Winthrop, Hull, Weymouth, Braintree, and Quincy. In Boston, deep flooding affects the Seaport District including Atlantic Avenue, Long Wharf, and the Aquarium MBTA Station. Flooding will occur several hours before and after high tide. Follow the instructions of local officials and evacuate if asked to do so. Find alternate travel routes.
14.5 ft
This is a serious flood situation. Many coastal roads become impassable. Flooding 2 to 3 feet deep affects roads and homes in low lying areas in Revere, Winthrop, Hull, Weymouth, Braintree, and Quincy. In Boston, flooding affects the Seaport District including Long Wharf and the Aquarium MBTA Station. Splashover and debris washes onto coastal roads when large waves occur.
14 ft
Many coastal roads become impassable. Flooding 1 to 3 feet deep affects coastal roads and some homes in low lying areas in Revere, Winthrop, Hull, Weymouth, Braintree, and Quincy. In Boston, flooding affects portions of the waterfront including Long Wharf and the Aquarium MBTA Station. Splashover and debris washes onto coastal roads when large waves occur.
13.5 ft
Some vulnerable coastal roads become impassable around high tide. Flooding 1 to 2 feet deep affects some coastal roads and low lying areas from Revere and Winthrop through Boston to Hull, Braintree, and Quincy. Splashover and debris may wash onto coastal roads when large waves occur.
12.5 ft
Shallow pockets of flooding less than one foot deep affects the lowest lying areas, including Morrissey Boulevard in Boston.
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 |
|---|---|---|
| Jan 4, 2018 | 15.16 ft | — |
| Feb 6, 1978 | 15.1 ft | — |
| Mar 2, 2018 | 14.67 ft | — |
About This Gauge
NWS LID
BHBM3
River
Boston Harbor
County
Suffolk, MA
Coordinates
42.3539°N, 71.0503°W
Get Flood Alerts for Boston 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 Boston Harbor at Boston (IN MLLW)?
The Boston Harbor at Boston (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 Boston Harbor at Boston (IN MLLW)?
The NWS-defined flood stage for Boston Harbor at Boston (IN MLLW) is 12.5 feet. Action stage begins at 11.5 feet. Moderate flooding starts at 14 feet, and major flooding at 15 feet.
How do I get alerts when Boston Harbor rises?
Download StormCast free on Google Play, go to River Gauges, and add Boston Harbor at Boston (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 Boston Harbor at Boston (IN MLLW) gauge located?
The gauge is located in Suffolk County, Massachusetts at coordinates 42.3539°N, 71.0503°W. Data is provided by the U.S. Geological Survey and the National Weather Service.
More Resources
Source & Notes
Data provided by: NOAA CO-OPS
- <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>