Suffolk County, MA flood risk and natural hazards

Suffolk County in the state and national rankings

National placement for Suffolk County is #262 of 3,232, with an expected annual loss estimate of about $114.9 million. A #5 of 14 state ranking accompanies its 7.8% share of the Massachusetts loss total. The modeled $114.9 million annual average does not predict the loss in any single year. Lancaster County, NE ranks immediately above it, with about $115.4 million in modeled annual loss. The next lower national total is about $114.8 million, in Sangamon County, IL. The next higher total within Massachusetts belongs to Norfolk County, MA, at about $146.9 million. That puts the estimates about $32.0 million apart, with 9.9% of state loss in the comparison county. The next lower total within Massachusetts belongs to Plymouth County, MA, at about $114.3 million. The dollar gap is about $564,000; that county accounts for 7.7% of statewide modeled loss.

Massachusetts county comparisons

Suffolk County hazard estimates

Riverine Flood

The national loss rank for riverine flooding is #214 of 3,232, based on about $59.5 million in modeled expected annual loss. Its 51.8% share of total loss comes with a state loss rank of #8 of 14; FEMA assigns a Relatively High rating; for riverine flooding, 7 state counties and 186 US counties share that label.

Hurricane

With about $12.9 million in modeled expected annual loss from hurricanes, the county ranks #201 of 2,485 in the national comparison. In Massachusetts, this estimate ranks #7 of 14 and represents 11.2% of the county’s modeled loss; FEMA assigns a Relatively High rating; the Relatively High label covers 6 state counties and 118 nationally for hurricanes.

Earthquake

The national loss rank for earthquakes is #190 of 3,232, based on about $11.7 million in modeled expected annual loss. This hazard makes up 10.1% of the total; FEMA assigns a Relatively Moderate rating, and its loss ranks #3 of 14 in Massachusetts; for earthquakes, 5 state counties and 250 US counties share that label.

Heat Wave

With about $9.4 million in modeled expected annual loss from heat waves, the county ranks #94 of 3,202 in the national comparison. Its 8.2% share of total loss comes with a state loss rank of #1 of 14; FEMA assigns a Relatively High rating; for heat waves, 1 state county and 98 US counties share that label.

Cold Wave

With about $8.7 million in modeled expected annual loss from cold waves, the county ranks #238 of 3,232 in the national comparison. In Massachusetts, this estimate ranks #3 of 14 and represents 7.6% of the county’s modeled loss; FEMA assigns a Relatively High rating, matching 302 US counties, including 3 in Massachusetts, for this hazard.

Coastal Flood

The national loss rank for coastal flooding is #48 of 588, based on about $6.3 million in modeled expected annual loss. Its 5.5% share of total loss comes with a state loss rank of #4 of 9; FEMA assigns a Relatively High rating; the Relatively High label covers 2 state counties and 60 nationally for coastal flooding.

Between riverine flooding and hurricanes, the modeled dollar gap is about $46.6 million; their shares differ by 40.6 percentage points. Between hurricanes and earthquakes, the modeled dollar gap is about $1.3 million; their shares differ by 1.1 percentage points. About $2.2 million separates earthquakes from heat waves in the local estimates, equivalent to 1.9 percentage points of county loss. The loss estimate for heat waves exceeds cold waves by about $755,000, equivalent to 0.7 percentage points of total loss. Between cold waves and coastal flooding, the modeled dollar gap is about $2.4 million; their shares differ by 2.1 percentage points.

Population and recorded values

FEMA counts 796,326 residents in Suffolk County, across about 121 square miles. About $133.09 billion is the building value amount in FEMA’s record. The recorded agricultural value is about $671,000. Total modeled loss averages about $144 per resident annually, compared with about $210 statewide. Its 11.3% share of state residents sits alongside 7.8% of of annual loss. Buildings account for 9.3% of recorded Massachusetts building value. By recorded residents per square mile, the county places 1 among 14 Massachusetts county records with population and area values. Those recorded totals give about 6,558 residents per square mile, versus about 659 across Massachusetts. The median county population in Massachusetts is about 497,824, compared with 796,326 locally. The county’s national shares are 0.2% for population and 0.1% for modeled loss. Per-person modeled loss is about $144 locally; the corresponding US average comes to about $459. About $108.5 million of annual loss falls within the six leading hazards, accounting for 94.4% of the total. The balance outside those six estimates is about $6.4 million, or 5.6% of total loss. The estimate for tornadoes ranks #6 of 14 in Massachusetts: about $2.6 million annually, in local position 7. Its national loss rank is #857 of 3,225, and it represents 2.3% of the county’s modeled loss. The county’s number 8 hazard by dollar loss is lightning: about $2.3 million, with a state rank of #2 of 14. This 2.0% slice of county loss ranks #104 of 3,222 across US counties.

FEMA labels and risk score

Suffolk County has a FEMA risk index score of about 93.5, ranking #205 of 3,144 nationally. The risk index rating is Relatively Moderate, a label shared by 8 of 14 Massachusetts counties. FEMA labels expected annual loss as Relatively Moderate, matching 7 county records across Massachusetts. For social vulnerability, FEMA assigns Relatively High; 2 counties in Massachusetts have that label. For community resilience, FEMA assigns Very High; 13 counties in Massachusetts have that label. Its risk score ranks #4 of 14 within Massachusetts, while its loss total ranks #5 of 14. The Relatively High vulnerability and Very High resilience pairing appears in 1 Massachusetts counties. Those counties together hold 7.8% of Massachusetts modeled loss, including this county’s 100.0% share of their total. On the state risk-score list, Worcester County, MA sits immediately above, scoring about 93.5 and ranking #3 of 14. Its share of statewide modeled loss is 11.0%; FEMA’s risk index label there is Relatively Moderate. Hampden County, MA is next below it by state risk score, at about 92.8; that record ranks #5 of 14. For that neighboring score, the risk index category is Relatively Moderate, and the county’s state loss share is 7.2%. Across the US, this social vulnerability category, Relatively High, covers 15.4% of residents in 630 counties. Across the US, this community resilience category, Very High, covers 27.2% of residents in 629 counties. Across the county’s hazard ratings, 1 carry Very High: lightning. The county’s Relatively High group contains 5 hazards: coastal flooding, cold waves, heat waves, hurricanes, riverine flooding. Across the county’s hazard ratings, 5 carry Relatively Moderate: earthquakes, hail, ice storms, strong wind, tornadoes. FEMA assigns Relatively Low to 1 hazard here, covering winter weather. Across the county’s hazard ratings, 2 carry Very Low: landslides, wildfires.