Enter any address in Merrimack County, New Hampshire to see its FEMA flood zone
Flash flooding from heavy rainfall events is a primary flood concern in Merrimack County. Over the past 30 years, NOAA Storm Events data shows 81 flood events and 30 flash flood events, alongside 2 tropical storm events. For example, in June 2025, heavy rain and thunderstorms brought up to 4 inches of rainfall, causing flash flooding with road washouts and property damage. In May 2025, a low-pressure system produced 2 to 4 inches of rain in localized areas, leading to road closures due to saturated soils.
National Flood Insurance Program (NFIP) claims data indicates that properties in Zone A have experienced the most claims, with an average payout of $20,492 and an average water depth of 9.3 feet. Properties in Zone X_SHADED have seen higher average payouts ($25,447) but lower average water depths (1.8 feet). Homeowners in Zone A, and those in Zone X_UNSHADED with an average water depth of 11.6 feet, should pay particular attention to flood risk.
Summary generated from NOAA storm narratives and NFIP claim data for this county. Not predictive.
44 NOAA storm reports from this county describe what happened, in the words of the meteorologists who were there.
Merrimack County, New Hampshire has recorded 113 flood-related events since 1996 according to NOAA's Storm Events Database, including 30 flash floods and 81 river or area floods. The county has received 29 federal disaster declarations, 5 of which involved flooding or coastal storms. Enter any address above to check its FEMA flood zone designation.
FEMA Disaster Declarations (1973–2020)
Source: OpenFEMA Disaster Declarations Summaries.
| Declaration | Type | Date |
|---|---|---|
| Covid-19 | Biological | Jan 20, 2020 |
| Covid-19 Pandemic | Biological | Jan 20, 2020 |
| Severe Storm And Flooding | Severe Storm | Oct 29, 2017 |
| Severe Winter Storm And Snowstorm | Severe Storm | Feb 8, 2013 |
| Hurricane Sandy | Hurricane | Oct 26, 2012 |
| Severe Storm | Severe Storm | Oct 29, 2011 |
| Hurricane Irene | Hurricane | Aug 26, 2011 |
| Tropical Storm Irene | Hurricane | Aug 26, 2011 |
| Severe Winter Storm | Severe Storm | Feb 23, 2010 |
| Severe Winter Storm | Severe Storm | Dec 11, 2008 |
NOAA Storm Events Database (1996–2025)
Source: NOAA National Weather Service Storm Events Database.
| Type | Date | Damage |
|---|---|---|
| Flood | May 31, 2025 | 0.00K |
| Flash Flood | Jun 6, 2025 | 0.00K |
| Flash Flood | Jul 29, 2023 | 0.00K |
| Flash Flood | Jun 28, 2023 | 0.00K |
| Flood | Jul 17, 2023 | 0.00K |
| Flash Flood | Jul 16, 2023 | 0.00K |
| Flood | Jul 11, 2023 | 0.00K |
| Flood | Jul 10, 2023 | 0.00K |
| Flash Flood | Jul 8, 2023 | 0.00K |
| Flood | Jul 3, 2023 | 0.00K |
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...
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, s...
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 l...
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 ...
Flood — Jul 17, 2023
On the evening of July 15th isolated thunderstorms developed across southern New Hampshire. Storm movement mitigated flash flooding across the state, except for the city of Manchester where multiple storms traveled directly over the city on the evening of July 15th. Up to 2��� fell in an hour over the urban city area. The intense rainfall rates lead to rapid run-off and caused localize...
Source: NOAA National Weather Service Storm Events Database.
Source: OpenFEMA NFIP Individual Claims (2.25M records analyzed).
FEMA assigns flood zone designations to areas in Merrimack County, New Hampshire:
AE High Risk — 1% annual chance of flooding. Insurance required.
VE Very High Risk — Coastal flooding with wave action.
X (Shaded) Moderate Risk — 500-year floodplain.
X Low Risk — Outside major floodplains.
Properties in Merrimack County, New Hampshire that are in FEMA-designated Special Flood Hazard Areas (zones A and V) with federally backed mortgages are required to carry flood insurance.
Even outside high-risk zones, flood insurance is recommended. From 2014 to 2024, nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area.
Visit FloodSmart.gov to find an agent and get a quote.