420
Recorded events
10
Counties affected
5
Direct deaths
$93.0M
Property damage
New Hampshire flash flood history: 420 recorded events across 10 counties between 1996 and 2025.
Decade by decade
New Hampshire flash flood history by decade
The 2020s are the busiest decade on record with 187 reported flash flood events across New Hampshire. Earlier decades are thinner because systematic reporting for this hazard expanded over time, not because the weather was calmer.
County ranking
Counties with the most flash flood events in New Hampshire
| Rank | County | Events | Deaths | Damage | Span |
|---|---|---|---|---|---|
| #1 | Grafton County | 107 | 2 | $34.9M | 1996–2024 |
| #2 | Coos County | 60 | 0 | $10.1M | 1996–2024 |
| #3 | Cheshire County | 58 | 2 | $18.9M | 2003–2024 |
| #4 | Hillsborough County | 51 | 0 | $2.9M | 1996–2025 |
| #5 | Carroll County | 38 | 0 | $5.6M | 1996–2024 |
| #6 | Merrimack County | 29 | 0 | $3.1M | 1996–2025 |
| #7 | Belknap County | 25 | 1 | $3.9M | 1996–2023 |
| #8 | Sullivan County | 24 | 0 | $5.9M | 1996–2023 |
| #9 | Rockingham County | 13 | 0 | $5.2M | 1996–2024 |
| #10 | Strafford County | 10 | 0 | $2.4M | 1996–2021 |
Significant events
Deadliest flash flood events in New Hampshire
| Date | County | Scale | Deaths | Injuries |
|---|---|---|---|---|
| Oct 9, 2005 | Cheshire County | — | 2 | 0 |
| Jun 27, 1998 | Grafton County | — | 1 | 1 |
| Aug 7, 2008 | Belknap County | — | 1 | 2 |
| Jul 13, 1996 | Grafton County | — | 1 | 0 |