Enter any address in Hillsborough County, New Hampshire to see its FEMA flood zone
Flash flooding from heavy rainfall events is the most frequent type of flooding in Hillsborough County, NH, with 51 such events recorded in the last 30 years, alongside 44 general flood events and 3 tropical storms. For example, a slow-moving low-pressure system brought between 2 and 3 inches of rain to the county on May 10, 2025, causing flooding due to saturated ground and elevated stream flows. Another event on June 6, 2025, saw up to 4 inches of rain in a few hours, leading to flash flooding, washed-out roads, and property damage.
National Flood Insurance Program (NFIP) data shows that properties in Zone A have experienced the most claims, with 272 claims averaging $18,913. However, properties in Zone X, which includes both shaded and unshaded areas, have also seen significant claims, averaging $14,983 and $11,385 respectively, with water depths in Zone X averaging 10.0 feet. Homeowners in areas designated as Zone A, or those in any zone experiencing significant water depth and payouts, should pay particular attention to flood risk.
Summary generated from NOAA storm narratives and NFIP claim data for this county. Not predictive.
60 NOAA storm reports from this county describe what happened, in the words of the meteorologists who were there.
Hillsborough County, New Hampshire has recorded 98 flood-related events since 1996 according to NOAA's Storm Events Database, including 51 flash floods and 44 river or area floods. The county has received 31 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 Winter Storm And Snowstorm | Severe Storm | Jan 26, 2015 |
| Severe Winter Storm And Snowstorm | Severe Storm | Feb 8, 2013 |
| Hurricane Sandy | Hurricane | Oct 26, 2012 |
| Severe Storm | Severe Storm | Oct 29, 2011 |
| Severe Storm And Snowstorm | Severe Storm | Oct 29, 2011 |
| Hurricane Irene | Hurricane | Aug 26, 2011 |
| Severe Storms And Flooding | Severe Storm | Mar 14, 2010 |
| Severe Winter Storm | Severe Storm | Feb 23, 2010 |
NOAA Storm Events Database (1996–2025)
Source: NOAA National Weather Service Storm Events Database.
| Type | Date | Damage |
|---|---|---|
| Flash Flood | Aug 13, 2025 | 0.00K |
| Flash Flood | Jul 12, 2025 | 5.00K |
| Flood | May 10, 2025 | 0.00K |
| Flash Flood | Jun 7, 2025 | 0.00K |
| Flash Flood | Jun 6, 2025 | 0.00K |
| Flash Flood | Aug 4, 2024 | 0.00K |
| Flash Flood | Jun 26, 2023 | 0.00K |
| Flash Flood | Jul 21, 2023 | 0.00K |
| Flood | Dec 18, 2023 | 0.00K |
| Flash Flood | Jul 16, 2023 | 0.00K |
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 u...
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...
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, s...
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...
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 Hillsborough 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 Hillsborough 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.