National Weather ServiceNew HampshireFlash Flood WarningArchive to October 1, 2026
Flash Flood Warnings in New Hampshire
The National Weather Service issued 6 flash flood warnings for New Hampshire in 2025 and 15 a year on average in 2008-2025; in 2021-2025 it had the 42nd most of any state. 2026 through September: 3, 79% below the average of 14 for those months in 2008-2025. Grafton was covered most often (90 times since 2008).
How many flash flood warnings does New Hampshire get?
Every flash flood warning that covered part of New Hampshire. 2026 is an outline: the year is not over.
The numbers
| Year | Count |
|---|---|
| 2026 (through September) | 3 |
| 2025 | 6 |
| 2024 | 13 |
| 2023 | 59 |
| 2022 | 1 |
| 2021 | 14 |
| 2020 | 21 |
| 2019 | 6 |
| 2018 | 11 |
| 2017 | 18 |
| 2016 | 6 |
| 2015 | 11 |
| 2014 | 25 |
| 2013 | 36 |
| 2012 | 11 |
| 2011 | 7 |
| 2010 | 1 |
| 2009 | 7 |
| 2008 | 15 |
Source: Iowa Environmental Mesonet archive of National Weather Service watches, warnings and advisories (VTEC); National Weather Service. Data as of October 1, 2026.
When in the year does New Hampshire get them?
Sum of 2008-2025; the busiest month is labelled.
Source: Iowa Environmental Mesonet archive of National Weather Service watches, warnings and advisories (VTEC); National Weather Service. Data as of October 1, 2026.
Where in New Hampshire?
| County or forecast zone | Since 2008 | Since 2023 | Last issued |
|---|---|---|---|
| Grafton | 90 | 23 | June 11, 2026 |
| Carroll | 67 | 20 | June 11, 2026 |
| Coos | 64 | 20 | August 8, 2026 |
| Hillsborough | 63 | 19 | August 3, 2026 |
| Cheshire | 60 | 18 | July 12, 2025 |
| Merrimack | 53 | 14 | August 3, 2026 |
| Belknap | 45 | 10 | July 29, 2023 |
| Rockingham | 38 | 15 | August 3, 2026 |
| Sullivan | 31 | 10 | May 21, 2024 |
| Strafford | 26 | 8 | August 3, 2026 |
The NWS issues these products for counties or forecast zones; a zone can be part of a county or a mountain range.
Source: Iowa Environmental Mesonet archive of National Weather Service watches, warnings and advisories (VTEC); National Weather Service. Data as of October 1, 2026.
The latest flash flood warnings for New Hampshire in AreaZine's record
NWS GrayWarningAugust 8, 2026
Flash Flood Warning: Coos, NH
Expired 9:30 p.m. EDT, August 8, 2026
NWS GrayWarningAugust 3, 2026
Flash Flood Warning: Hillsborough, Merrimack, Rockingham and 1 more, NH
Expired 11:15 a.m. EDT, August 3, 2026
NWS GrayWarningJune 11, 2026
Flash Flood Warning: Carroll and Grafton, NH
Expired 3:45 a.m. EDT, June 11, 2026
This list is AreaZine's record of the NWS alert feed, kept since April 6, 2026; the counts above come from the complete IEM archive.
Source: National Weather Service alerts (api.weather.gov).
What is a flash flood warning?
A flash flood warning means flash flooding is happening or about to happen: water rising fast in streams, streets or dry washes, usually within six hours of heavy rain or a dam or levee failure. A warning means the hazard is happening, about to happen, or very likely: act now to protect people and property. The national record · Every warning type in New Hampshire.