Merrimack County

Every recorded tornado

1. Injuries and deaths are for the tornado’s whole path, which may extend beyond the county. Deaths recorded within Merrimack County: 0.
2. Weak tornadoes were under-recorded before Doppler radar coverage became national in the early 1990s, so earlier decades read low. Ratings use the Fujita scale before February 2007 and the Enhanced Fujita scale after.

Storm Prediction Center severe weather database, 1950 to 2025.

Every storm within 100 miles

1. Tropical storms and hurricanes (34 kt or more, still tropical) at closest approach. Post-tropical remnants with gale-force winds are listed but not counted. Direct: track within 50 miles; near: within 100 miles. Distance is measured to the county boundary for counties and to the city centre for cities, using positions interpolated hourly between HURDAT2 fixes.

National Hurricane Center HURDAT2, 1851 to 2025.

Smoke overhead

1. A smoke day is a date on which a smoke plume traced by NOAA Hazard Mapping System analysts from satellite imagery covered this place's point (the county's population centre or the city centre). Counts here are of medium or heavy smoke. Since 2018 analysts have often drawn light smoke as one area over most of the continent, so light-smoke counts are not comparable from year to year. The plumes show smoke anywhere in the air above, not air quality at the ground, and smoke hidden by cloud is missed.

NOAA Hazard Mapping System smoke analysis, 2011 to 2026, retrieved October 30, 2026.

Claims by ZIP code

This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).

OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026. NOAA Storm Events through 2026.

River crests

River gauges

1. Crests are the highest and the recent crests the National Weather Service lists for each river gauge in the county that has a flood stage, not every flood. Flood categories use each gauge's current flood stages; crests from before levees, dams or channel changes may not be comparable. Crests measured on an old datum are left out of the rankings.

NOAA National Water Prediction Service gauge records, retrieved October 30, 2026.

1. The Palmer Drought Severity Index is computed by NOAA each month from the county's average temperature and precipitation, relative to the county's own climate. Zero is normal; -3 or lower is severe drought and -4 or lower extreme drought. It describes the long-term balance of moisture, not water supply or crop losses.

NOAA NCEI nClimDiv county Palmer Drought Severity Index, 1895 to September 2026, issued October 6, 2026.

Every earthquake of magnitude 4 or more within 50 miles

1. Earthquakes of magnitude 2.5 or more in the USGS Comprehensive Catalog since 1900. Within 50 miles means the epicentre lies within 50 miles of the county boundary (or inside the county).
2. Small earthquakes were under-recorded before the modern seismic networks of the 1970s and are still missed in remote areas, so early decades read low. Magnitudes are as the catalogue reports them and mix scales (moment, local and body-wave).

USGS ANSS Comprehensive Earthquake Catalog, 1900 to present, retrieved October 30, 2026.

Mapped landslides

Mapped by NASA (1).

1. Landslides mapped in the USGS compilation of landslide inventories across the United States (version 3.0, 2025), rated probable or better. The compilation joins inventories made by federal and state agencies for different purposes and areas, so the number mapped in a county reflects how closely it has been surveyed as much as how often its slopes fail. An area with few records may simply not have been mapped. Deaths are as recorded in the inventories; a slide listed in two inventories is counted once.

USGS Landslide Inventories across the United States, version 3.0, retrieved October 27, 2026.

More event types since 1996

Costliest events since 1996

1. Jan 7, 1998Ice Storm, Merrimack$3.7 million
   National Weather Service narrative

   A severe ICE STORM hit sections of New Hampshire from January 7 through January 9. The hardest hit areas in northern and central New Hampshire were generally between about 1000 and 2000 ft above sea level. While many cities and towns at lower elevations received only rain, towns at higher elevations, such as New London, where the temperatures were slightly cooler had freezing rain. Ice accreted several inches thick on trees, power lines, and other exposed surfaces causing many people in those areas to lose electrical service. Statewide, the storm knocked out power to about 55,000 customers, an estimated 125,000 people. During the time without power, residents and those involved…

2. Jul 9, 1997Lightning$3.0 million
   National Weather Service narrative

   Lightning ignited a massive 21 alarm fire between 4:00 and 4:30 pm that gutted a lumber mill in Bradford. More than 200 firefighters and 50 fire trucks battled the blazed that completely destroyed the lumber yard.

3. Oct 20, 1996Flash Flood$2.2 million
   National Weather Service narrative

   A coastal storm which was fed tropical moisture by the circulation around Hurricane Lily produced between 7 and 9 inches of precipitation throughout the County during a 30-hour period. Many homes and businesses were flooded. Roads and bridges were washed out.

4. Feb 25, 2010Flood$1.7 million
   National Weather Service narrative

   Heavy rain caused county wide flooding of small rivers and streams in Merrimack County New Hampshire.

5. Dec 11, 2008Ice Storm, Merrimack$1.6 million
   National Weather Service narrative

   A major winter storm brought a mixture of snow, sleet, and freezing rain to New Hampshire from the morning of December 11th to the morning of December 12th. The greatest impact in the state was in southern and central New Hampshire where a significant ice storm occurred. Following the ice storm, recovery and restoration efforts were negatively impacted by additional winter weather events that passed through the state. ||The ice storm was caused by an area of low pressure that moved northeastward along a stalled frontal boundary off the East Coast. Near ground level, cold air from eastern Canada funneled southward into the region on northerly winds. Southerly winds at higher levels…

6. Apr 16, 2007Flood$1.0 million
   National Weather Service narrative

   Overview: An area of low pressure intensified rapidly as it moved slowly from the southeastern United States on the morning of Sunday, April 15th to near New York City by the morning of Monday, April 16th. The intense low over New York City in combination with high pressure over eastern Canada produced a very intense pressure gradient across the area which caused strong east to northeast winds to develop across the region. Over land, the strong winds downed numerous trees. The downed trees caused widespread power outages, especially near the coast, and numerous road closures. Over the marine areas, the strong winds caused a storm surge and large ocean waves of up to 30 feet to…

7. Oct 8, 2005Flood, Merrimack$1.0 million
   National Weather Service narrative

   The interaction between a cold frontal boundary and the remnants of Tropical Storm Tammy resulted in tremendous amount of rainfall throughout most of central and southern New Hampshire. Rainfall ranged from just under 2 inches in far northern New Hampshire to 9 inches at Gilford in Belknap County. An unofficial report was received of 12.75 inches near Gunstock Ski area. There was a tremendous amount of damage to roads and bridges, and to the infrastructure in general due to flooding of small rivers and streams. Homes and businesses were damaged. Tragically, two young people lost their lives in the town of Unity in Sullivan County when they attempted to drive over a bridge that had…

8. Aug 28, 2011Flood$900,000
   National Weather Service narrative

   Heavy rain from Tropical Storm Irene caused flooding on small rivers and streams throughout Merrimack County.

9. May 13, 2006Flood$750,000
   National Weather Service narrative

   Low pressure developed south of New England and remained nearly stationary from the 12th to the 15th resulting in over 12 inches of rain in some locations in a 72 hour period. Homes and businesses were damaged extensively. Many roads were washed out and impassable. Some bridges were damaged or destroyed. Several evacuations and rescues took place during the flood event. Two dams on the Salmon Falls River were being monitored as it was feared they may fail.

10. Mar 14, 2010Flood$440,000
    National Weather Service narrative

    Heavy rain caused widespread flooding of small rivers and streams throughout Merrimack County.

1. Storm Events records before 1996 cover only tornadoes, thunderstorm wind and hail. Damage figures are as reported by the National Weather Service at the time, not adjusted for inflation.

NOAA NCEI Storm Events Database, 1950 to 2026, issued October 26, 2026.

All-time high

102°FJul 3, 1966

All-time low

−37°FFeb 16, 1943

Warmest night

75°F4 times, most recently Jul 11, 2024

Coldest day

−4°FFeb 15, 1943

Wettest day

5.12 inMay 13, 2006

Snowiest day

25.6 inDec 17, 2020

Hottest year

2024mean 49.6°F

Coldest year

1976mean 43.2°F

Wettest year

200857.97 in

Driest year

196524.17 in

Snowiest season

118.0 in2007-08

Station Concord Asos (USW00014745), 338 ft elevation, 5.0 miles from the population centre. Daily records from 1939 to October 26, 2026; 99.9% of days in the last 30 years are complete. Records at a single station can differ from a city’s official threaded record, which may combine several stations.

NOAA NCEI Global Historical Climatology Network Daily.

This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).

OpenFEMA Disaster Declarations Summaries, retrieved October 30, 2026. Statewide declarations are not listed.

Neighbouring counties

• Tornadoes NOAA Storm Prediction Center severe weather database, through 2025.
• Tropical cyclones NOAA National Hurricane Center HURDAT2 (Atlantic; Northeast and Central Pacific), through 2025.
• Wildfire USGS/USFS Monitoring Trends in Burn Severity, through 2026.
• Storm events NOAA NCEI Storm Events Database, through 2026.
• Flood insurance OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026.
• Declarations OpenFEMA Disaster Declarations Summaries v2, retrieved October 30, 2026.
• Weather records NOAA NCEI Global Historical Climatology Network Daily, station USW00014745.
• River crests NOAA National Weather Service, National Water Prediction Service river gauges, retrieved October 30, 2026.
• Drought NOAA NCEI nClimDiv county Palmer Drought Severity Index, through September 2026.
• Smoke NOAA NESDIS Hazard Mapping System smoke analysis, retrieved October 30, 2026.
• Landslides USGS Landslide Inventories across the United States, version 3.0 (2025).
• Earthquakes USGS ANSS Comprehensive Earthquake Catalog (ComCat), retrieved October 30, 2026.

Joins, thresholds and known limits are set out in the methodology. Found an error? Report it. Page built October 30, 2026.