629 flood insurance claims·$9.8M paid·6 federal flood & hurricane disasters
Share of the whole county outline, rivers and lakes included; parts FEMA hasn’t mapped count as zero.
Shaded areas are FEMA’s mapped flood hazard zones in and around Hillsborough County, New Hampshire. Zoomed out they are simplified; at street level the map switches to FEMA’s exact layer. Tap anywhere to check that spot, or search an address above.
Flash flooding and general riverine flooding from heavy rain systems dominate the flood risk profile in Hillsborough County, supported by NOAA records detailing 51 flash flood events, 44 general floods, and 3 tropical storms over the last 30 years. Recent events illustrate this vulnerability, including a slow-moving low pressure system in May 2025 that dropped 2 to 3 inches of rain onto saturated ground, and a stationary front in June 2025 that brought up to 4 inches of rain—with rates exceeding 2 inches per hour—causing road washouts, property damage, and multiple flooded roads.
National Flood Insurance Program records show significant claim activity across multiple zones. High-risk Zone A accounts for 323 claims with an average payout of $24,847 and an average recorded water depth of 16 inches. Moderate- to low-risk zones also experience impacts: Zone X recorded 126 claims averaging $17,856 and 16 inches of water depth, Shaded Zone X recorded 79 claims averaging $18,279 and 18 inches of water depth, Unshaded Zone X recorded 66 claims averaging $16,474 and 8 inches of water depth, and Unknown zones recorded 35 claims averaging $9,822 and 2 inches of water depth. Homeowners, real estate agents, and journalists should pay the most attention to properties in Zone A, as well as structures in various Zone X classifications where historical claims demonstrate that moderate- and low-risk zones are still subject to property damage and standing water.
Summary written from NOAA storm reports and NFIP claims for this county. Not a prediction.
31% of Hillsborough County’s flood insurance claims were on properties rated outside FEMA’s high-risk zones.
468 NFIP claims with a recorded rated flood zone, 1978 to date. The zone is the one FEMA used to rate that policy, which may not match today’s map. Source: OpenFEMA NFIP claims.
In flood insurance claims here that reported a flood depth, the average was 15 inches.
Drawn to scale against an 80-inch door. Even a few inches soaks flooring, the bottom of the drywall and anything plugged in near the floor.
Average of the depths reported on claims (zero and implausible values left out); FEMA’s record doesn’t say exactly where each depth was measured. Source: OpenFEMA NFIP claims.
The worst year was 2006, with 165 claims and $4.6M paid, the year of Severe Storms and Flooding.
Bar height is scaled by square root so ordinary years stay visible next to the worst one. NFIP claims by year of loss. Source: OpenFEMA.
60 NOAA storm reports from Hillsborough County describe what happened, in the words of the forecasters who covered it. Read the New Hampshire flood stories →
31 federal disaster declarations since 1973, 6 of them floods, coastal storms or hurricanes.
| Disaster | Began |
|---|---|
| Severe Winter Storm And Snowstorm | Jan 26, 2015 |
| Severe Winter Storm And Snowstorm | Feb 8, 2013 |
| Hurricane Sandy | Oct 26, 2012 |
| Severe Storm | Oct 29, 2011 |
| Severe Storm And Snowstorm | Oct 29, 2011 |
| Hurricane Irene | Aug 26, 2011 |
| Severe Storms And Flooding | Mar 14, 2010 |
| Severe Winter Storm | Feb 23, 2010 |
Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.
98 since 1996: 51 flash floods and 44 river or area floods.
| Event | Date | Damage |
|---|---|---|
| Flash Flood | Aug 13, 2025 | — |
| Flash Flood | Jul 12, 2025 | $5,000 |
| Flood | May 10, 2025 | — |
| Flash Flood | Jun 7, 2025 | — |
| Flash Flood | Jun 6, 2025 | — |
| Flash Flood | Aug 4, 2024 | — |
| Flash Flood | Jun 26, 2023 | — |
| Flash Flood | Jul 21, 2023 | — |
— = no damage estimate in the record. Source: NOAA Storm Events Database.
Flash Flood · Aug 13, 2025. The region was experiencing well above normal temperatures, with high temperatures reaching the low to mid-90s. This created a very warm, humid, and unstable atmosphere. A pre-frontal surface trough moved into NH on the afternoon of August 13th, triggering numerous thunderstorms, a few of the storms became severe in nature. In addition, very heavy rain fell in Nashua area, causing some minor urban flooding.
Flash Flood · Jul 12, 2025. A hot and moist airmass was firmly in place across Southern New Hampshire on July 12th. Overall instability was limited but terrain driven thunderstorms did develop around Mount Monadnock and trained over this region. Localized road damage due flash flooding was reported.
Flood · May 10, 2025. A slow moving low pressure system tracked across the region between the 9th and the 10th. The region was vulnerable to flooding due to saturated ground conditions and elevated stream flows from days of on and off again rainfall. The event was drawn out with a fairly steady rain with rates <0.5/hr. There was a period of heavier rainfall as the system received jet enhancement as it lifted to the northeast. Rainfal…
Flash Flood · Jun 7, 2025. A stationary front stalled over southern New Hampshire on the evening of June 6 into midday on June 7th. Repeated rounds of heavy rain and thunderstorms brought up to 4 inches of rainfall to areas across Merrimack and Hillsborough Counties between 3 and 7 PM. The heavy rain with rates measured over 2 inches per hour at times, was sufficient to cause flash flooding with multiple roads flooded, some with washouts, a…
National Weather Service narratives, lightly trimmed. Source: NOAA Storm Events Database.
Every colour on the map above is a place on this drawing: where the ground sits relative to the flood FEMA plans for.
If a building in Hillsborough County is in a high-risk zone (A or V) and its mortgage comes from a federally regulated or insured lender, or is federally backed, flood insurance is required.
Outside those zones it is optional, and often worth having: from 2014 to 2024 nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area. Since Risk Rating 2.0, NFIP premiums are set for each building, so the only reliable price is a quote: FloodSmart.gov or a local agent.