Hillsborough County, New Hampshire: Natural Disaster Risk and History
Hillsborough County, New Hampshire has a Relatively Moderate natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 89.8 out of 100, higher than about 89% of US counties, with ice storms, lightning and inland (river and flash) flooding scoring highest of its 18 hazards and $120 million a year in expected losses.
OpenFEMA lists 29 federal disaster declarations that included Hillsborough County since 1973, not counting 2 for COVID-19; the latest is DR-4209-NH (Severe Winter Storm and Snowstorm, declared 25 March 2015). NOAA's Storm Prediction Center recorded 20 tornadoes touching Hillsborough County from 1950 to 2025.
Live weather alerts for New Hampshire All official warnings Latest FEMA declarations
Population 422,867 Buildings worth $87 billion Area 902 sq mi Risk rank in New Hampshire 1 of 10 FIPS 33011
All 18 hazards, highest risk first
FEMA National Risk Index| Hazard | Risk rating | Score | Expected loss a year | How often | Events in record |
|---|---|---|---|---|---|
| Ice storm | Very High | 95.4 | $2.5 million | about 2.1 a year | 144 |
| Lightning | Relatively High | 93.2 | $2.2 million | about 21 a year | 174,519 strikes |
| Inland flooding | Relatively Moderate | 92.6 | $76 million | about 1.7 a year | 47 |
| Hurricane | Relatively Moderate | 92.6 | $18 million | about once every 8.7 years | 46 |
| Earthquake | Relatively Low | 88.2 | $5.8 million | about once every 546 years | — |
| Winter weather | Relatively High | 87.4 | $486,227 | about 19 a year | 352 |
| Strong wind | Relatively High | 86.9 | $2.5 million | about 1.1 a year | 40 |
| Landslide | Relatively Low | 84.2 | $39,187 | about once a year | — |
| Tornado | Relatively Moderate | 82.6 | $6.5 million | about once every 6.2 years | 8 |
| Heat wave | Relatively Low | 75.4 | $1.7 million | about 3.8 a year | 67 |
| Wildfire | Relatively Low | 67.0 | $203,767 | rarer than once in 1,000 years | — |
| Cold wave | Relatively Moderate | 66.2 | $2.6 million | about 1.7 a year | 33 |
| Drought | Relatively Low | 57.9 | $356,816 | about 4 a year | 210 |
| Hail | Relatively Low | 55.4 | $473,153 | about 2.4 a year | 90 |
| Avalanche | Very Low | 15.2 | $28 | about once every 100 years | 0 |
| Coastal flooding | Not Applicable | — | — | — | — |
| Tsunami | Not Applicable | — | — | — | — |
| Volcanic activity | Not Applicable | — | — | — | — |
Score: FEMA's percentile among US counties that face the hazard (higher = more risk). Expected loss: FEMA's modelled average yearly loss to buildings, people (as a statistical value) and crops. How often: FEMA's annualised frequency of the hazard in the county; for some hazards it counts event-days, so it is a rough guide, not a forecast. "Not Applicable" means FEMA does not model that hazard here.
Federal disaster declarations 29
Most common: Severe Storm 13, Snowstorm 6, Flood 5, Hurricane 4.
| Decade | Declarations | Incident types |
|---|---|---|
| 1970s | 1 | Flood |
| 1980s | 2 | Flood ×2 |
| 1990s | 6 | Severe Storm ×2, Flood ×2, Snowstorm, Hurricane |
| 2000s | 12 | Severe Storm ×5, Snowstorm ×5, Severe Ice Storm, Hurricane |
| 2010s | 8 | Severe Storm ×6, Hurricane ×2 |
The last 10
Widest declarations that included Hillsborough County
- Hurricane Sandy (2012, EM-3360-NH): 10 New Hampshire counties designated.
- Severe Storm (2011, EM-3344-NH): 10 New Hampshire counties designated.
- Hurricane Irene (2011, EM-3333-NH): 10 New Hampshire counties designated.
Named storms in its declarations: Hurricane Sandy (2012), Hurricane Irene (2011), Hurricane Katrina (2005), Hurricane Bob (1991).
Not counted above: 2 COVID-19 ("Biological") declarations — in 2020 every US county was included. New Hampshire also had 1 statewide declaration with no county list.
Tornado record since 1950 20
| Tornadoes touching the county | 20 |
|---|---|
| Strongest-rated | (E)F3 ×2 |
| Peak month | July (9) |
| Deadliest | 20 Aug 1968, F3, 1 mi path, 0 killed, 1 injured |
| Longest path | 20 May 1963, F3, 14 mi path |
| Most recent | 31 May 1998, F2, 0.5 mi path |
| Deaths / injuries on those paths | 0 / 1 |
| Rating | (E)F0 | (E)F1 | (E)F2 | (E)F3 | (E)F4 | (E)F5 | Unrated |
|---|---|---|---|---|---|---|---|
| Count | 1 | 12 | 5 | 2 | 0 | 0 | 0 |
| Decade | 1950s | 1960s | 1970s | 1980s | 1990s | 2000s | 2010s | 2020s |
|---|---|---|---|---|---|---|---|---|
| Count | 1 | 11 | 3 | 3 | 2 | 0 | 0 | 0 |
Deaths and injuries are for each tornado's whole path, which can run beyond this county. F-scale ratings before February 2007, Enhanced Fujita (EF) after.
How Hillsborough County compares with its 5 nearest counties
| County | Distance | Overall risk | Score | Top hazard |
|---|---|---|---|---|
| Hillsborough County (this page) | — | Relatively Moderate | 89.8 | Ice storm |
| Merrimack County | 43 km | Relatively Low | 78.2 | Ice storm |
| Cheshire County | 44 km | Relatively Low | 60.5 | Landslide |
| Rockingham County | 48 km | Relatively Moderate | 85.8 | Coastal flooding |
| Middlesex County, MA | 55 km | Relatively High | 96.9 | Ice storm |
| Sullivan County | 64 km | Very Low | 37.6 | Landslide |
Nearest by distance between county centres. Every county in New Hampshire, ranked.
Vulnerability and resilience
| Social vulnerability | Very Low 10.6 |
|---|---|
| Community resilience | Relatively High 64.3 |
| Community risk factor | 0.72 |
| Expected annual loss, all hazards | $120 million |
FEMA scales expected losses up where social vulnerability is high (people who may find it harder to prepare, evacuate or recover) and down where community resilience is high. A factor above 1 raises the risk score. For social vulnerability a high rating is worse; for resilience a high rating is better.
Prepare for Hillsborough County's main hazards
- Right now: National Weather Service alerts for New Hampshire · all official warnings on Global Incident Tracker.
- Ice storm: Power outages now · Carbon monoxide in winter
- Lightning: Weather alerts for New Hampshire
- Inland flooding: Flood safety: why shallow water kills · Floods recorded
- Your property's flood zone: FEMA Flood Map Service Center ↗ — this page cannot tell you that.
- Official preparedness guidance: Ready.gov ↗ and your county emergency management office.
What this page shows, and what it misses
FEMA's National Risk Index rates a whole county against every other US county; it is a planning-level estimate for nationwide comparison, not a flood-zone map and not a substitute for a local risk assessment or the risk to one home. Declarations are presidential disaster, emergency and fire management declarations that named this county; state declarations and SBA or USDA designations are not included. Tornadoes are counted when the county is one of up to four listed on the track; 670 tornadoes that crossed a state line carry no county list in NOAA's file and are left out.
Federal Emergency Management Agency (FEMA), National Risk Index Dataset: National Risk Index Counties - v1.20.0 (December 2025). Retrieved from https://services.arcgis.com/XG15cJAlne2vxtgt/ArcGIS/rest/services/National_Risk_Index_Counties/FeatureServer/0/query on November 2, 2026, 1:20 PM EST. This product uses the Federal Emergency Management Agency’s National Risk Index dataset API or downloadable datasets but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Federal Emergency Management Agency (FEMA), OpenFEMA Dataset: Disaster Declarations Summaries - v2, retrieved from https://www.fema.gov/api/open/v2/DisasterDeclarationsSummaries on November 2, 2026, 1:21 PM EST. This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Tornado records: NOAA/NWS Storm Prediction Center, Severe Weather Database, tornadoes 1950–2025 (https://www.spc.noaa.gov/wcm/data/1950-2025_actual_tornadoes.csv, downloaded 2 November 2026). Public domain; not endorsed by NOAA. Compiled by Global Incident Tracker.
Questions about Hillsborough County
What natural disasters is Hillsborough County, New Hampshire most at risk from?
Hillsborough County, New Hampshire has a Relatively Moderate natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 89.8 out of 100, higher than about 89% of US counties, with ice storms, lightning and inland (river and flash) flooding scoring highest of its 18 hazards and $120 million a year in expected losses.
How many federal disaster declarations has Hillsborough County had?
OpenFEMA lists 29 federal disaster declarations that included Hillsborough County since 1973, not counting 2 for COVID-19; the latest is DR-4209-NH (Severe Winter Storm and Snowstorm, declared 25 March 2015). Another 1 New Hampshire declarations were made statewide without a county list.
How many tornadoes have hit Hillsborough County?
NOAA's Storm Prediction Center recorded 20 tornadoes touching Hillsborough County from 1950 to 2025. The deadliest: 20 Aug 1968, F3, 1 mi path, 0 killed, 1 injured (deaths and injuries are for the whole path).
Is the National Risk Index a flood zone map?
No. The National Risk Index is a planning-level estimate for a whole county, built for nationwide comparison. It does not tell you the flood zone or the risk of a single property: for that, look up the address on FEMA's Flood Map Service Center (msc.fema.gov) and ask your local floodplain manager.