F0/EF0 1 2 3 4 5 · Lines run from where each tornado touched down to where it lifted; dots are short paths. Neighboring counties are outlined.
When tornadoes hit Grafton County
July has brought the most, 5 of 13. About 85% touched down between 12 pm and 6 pm (Central Standard Time, as the Storm Prediction Center records it).
By decade
More tornadoes in recent decades mostly reflects better detection and reporting (Doppler radar, storm spotters, damage surveys), especially for weak EF0 tornadoes, not necessarily more storms. The 2020s bar covers only 2020 to 2024.
How strong they were
| Rating | Estimated 3-second gust | Tornadoes |
|---|---|---|
| F0 / EF0 | Light damage: 65 to 85 mph (EF scale) | 4 |
| F1 / EF1 | Moderate: 86 to 110 mph | 6 |
| F2 / EF2 | Considerable: 111 to 135 mph | 2 |
| F3 / EF3 | Severe: 136 to 165 mph | 1 |
| F4 / EF4 | Devastating: 166 to 200 mph | 0 |
| F5 / EF5 | Incredible: over 200 mph | 0 |
Tornadoes before February 2007 were rated on the original Fujita (F) scale; since then the National Weather Service uses the Enhanced Fujita (EF) scale. Wind speeds above are EF-scale estimates from damage, not measurements. See what the EF scale means.
The strongest tornadoes in Grafton County
| Date | Rating | Path length | Path width | Deaths | Injuries |
|---|---|---|---|---|---|
| August 25, 1969 | F3 | 5.7 mi | 17 yd | ||
| August 11, 1966 | F2 | 9 mi | 100 yd | ||
| May 11, 1973 | F2 | 0.5 mi | 150 yd | ||
| July 14, 1963 | F1 | 0.1 mi | 83 yd | ||
| July 21, 1972 | F1 | 0.5 mi | 10 yd | ||
| July 21, 1972 | F1 | 7 mi | 10 yd | ||
| August 13, 1999 | F1 | 8 mi | 250 yd | ||
| August 21, 2011 | EF1 | 2.7 mi | 350 yd | ||
| July 16, 2024 | EF1 | 1.8 mi | 250 yd | ||
| June 27, 1964 | F0 | 0.5 mi | 17 yd |
Deaths and injuries are for each tornado’s whole path, which can cross other counties.
Most recent tornadoes
| Date | Rating | Path length | Path width | Deaths | Injuries |
|---|---|---|---|---|---|
| July 16, 2024 | EF1 | 1.8 mi | 250 yd | ||
| June 18, 2018 | EF0 | 0.2 mi | 20 yd | ||
| June 18, 2018 | EF0 | 9.4 mi | 25 yd | ||
| July 17, 2012 | EF0 | 0.5 mi | 30 yd | ||
| August 21, 2011 | EF1 | 2.7 mi | 350 yd | ||
| August 13, 1999 | F1 | 8 mi | 250 yd | ||
| May 11, 1973 | F2 | 0.5 mi | 150 yd | ||
| July 21, 1972 | F1 | 7 mi | 10 yd |
The official database ends with 2024. For storms since then, see the Storm Prediction Center’s reports and your local National Weather Service office.
FEMA’s tornado risk rating
FEMA’s National Risk Index rates the tornado risk in Grafton County as very low, with a score of 24 out of 100 compared with every other U.S. county. It estimates about 0.18 tornadoes a year here and an expected annual loss of about $378,430 to buildings, people and farming. The index mixes how often tornadoes strike with what is exposed and how well a community can recover, so a busy rural county can rate lower than a less active city.
Neighboring counties
- Belknap County, NH: 12 tornadoes
- Carroll County, NH: 10 tornadoes
- Coos County, NH: 8 tornadoes
- Sullivan County, NH: 7 tornadoes
- Merrimack County, NH: 7 tornadoes
- Windsor County, VT: 4 tornadoes
- Essex County, VT: 4 tornadoes
- Orange County, VT: 3 tornadoes
- Caledonia County, VT: 1 tornadoes
Staying safe
When a tornado warning is issued, act at once. Go to a basement, storm shelter or safe room. With none, use a small windowless room on the lowest floor, as far from outside walls as you can, and cover your head and neck. Mobile homes and cars are not safe places to ride out a tornado: leave early for a sturdy building or shelter. Read the full tornado safety guide and the National Weather Service advice linked below.
Sources
- NOAA Storm Prediction Center: Severe Weather Database, tornadoes 1950 to 2024 (public domain)
- FEMA National Risk Index, tornado county data (December 2025 release)
- NOAA Storm Prediction Center: The Enhanced Fujita Scale (EF scale)
- National Weather Service: Tornado safety
Sources last checked 1 November 2026.