299 flood insurance claims·$6.0M 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 Merrimack 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.
River flooding and flash flooding from heavy rainfall dominate the flood history of Merrimack County, supported by NOAA records documenting 81 flood events, 30 flash flood events, and 2 tropical storms over the last 30 years. Recent events illustrate this hazard, including a June 2025 flash flood caused by a stationary front that dropped up to 4 inches of rain—with rates exceeding 2 inches per hour—resulting in road washouts and property damage. Additionally, a strong low-pressure system in May 2025 produced 2 to 4 inches of rain over saturated soils, causing localized road closures.
National Flood Insurance Program claims data indicates that property owners in Zone A experienced the highest frequency of claims, totaling 175 claims with an average payout of $27,626 and an average recorded water depth of 16 inches. Properties in Zone X_SHADED also face notable risk, recording an average payout of $40,650 and an average water depth of 16 inches across 33 claims. Standard Zone X properties recorded 46 claims averaging $24,697 with an average depth of 12 inches, while unshaded Zone X properties saw 33 claims averaging $17,119 with a 13-inch average depth. Homeowners and real estate agents in Zone A and shaded Zone X areas should pay the closest attention to these flood risks.
Summary written from NOAA storm reports and NFIP claims for this county. Not a prediction.
27% of Merrimack County’s flood insurance claims were on properties rated outside FEMA’s high-risk zones.
241 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 89 claims and $2.3M 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.
44 NOAA storm reports from Merrimack County describe what happened, in the words of the forecasters who covered it. Read the New Hampshire flood stories →
29 federal disaster declarations since 1973, 6 of them floods, coastal storms or hurricanes.
| Disaster | Began |
|---|---|
| Severe Storm And Flooding | Oct 29, 2017 |
| Severe Winter Storm And Snowstorm | Feb 8, 2013 |
| Hurricane Sandy | Oct 26, 2012 |
| Severe Storm | Oct 29, 2011 |
| Hurricane Irene | Aug 26, 2011 |
| Tropical Storm Irene | Aug 26, 2011 |
| Severe Winter Storm | Feb 23, 2010 |
| Severe Winter Storm | Dec 11, 2008 |
Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.
113 since 1996: 30 flash floods and 81 river or area floods.
| Event | Date | Damage |
|---|---|---|
| Flood | May 31, 2025 | — |
| Flash Flood | Jun 6, 2025 | — |
| Flash Flood | Jul 29, 2023 | — |
| Flash Flood | Jun 28, 2023 | — |
| Flood | Jul 17, 2023 | — |
| Flash Flood | Jul 16, 2023 | — |
| Flood | Jul 11, 2023 | — |
| Flood | Jul 10, 2023 | — |
— = no damage estimate in the record. Source: NOAA Storm Events Database.
Flood · May 31, 2025. Strong low pressure system brought widespread soaking rains to the region, with most areas total rainfall amounts generally 1-1.25, with locally higher amounts in southern and central New Hampshire. A pivot point of the storm system occurred between Milford and Contoocook, resulting in rainfall amounts between 2 to 4 inches. This caused a handful of road closures due to flooding as antecedent rainfall over the p…
Flash Flood · Jun 6, 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…
Flash Flood · Jul 29, 2023. A stalled frontal boundary and surface low pressure began to slowly lift northward into the southeast New Hampshire through the Midcoast of Maine on the afternoon of the 29th. Showers and thunderstorms developed along the boundary and moved eastward. Since the system as a whole showed very little forward progression, multiple rounds of showers and thunderstorms ended up moving across the same locations multiple ti…
Flash Flood · Jun 28, 2023. Two rounds of rain moved across the state on June 28th with a weak frontal boundary. Light rain showers pushed through the state during the morning, with the first line of showers and thunderstorms moving into western New Hampshire by midday. This line slowly moved eastward through the early afternoon hours bringing a widespread band of heavy rain of 1 to 2���. As the axis of heavy rain moved into the Lakes…
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 Merrimack 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.