National Weather Service
National Weather Service United States Department of Commerce

Flooding in New Hampshire

On this page you learn what types of flooding are typical in New Hampshire and how do you protect yourself, your family and your home. You will also find out more about significant New Hampshire floods. Finally, you'll find links to NWS offices that provide forecast and safety information for New Hampshire, as well as links to our partners who play a significant role in keeping you safe.

Flooding Navigation bar, hover for links Flood Safety Home Page Turn Around Don't Drown Interactive Flood Map Types of flodding and associated risks NWS flood products forecasts and observations (AHPS) flood safety education and outreach partner agencies National Water Center flood city from plane, water up to roof tops

Significant New Hampshire Floods
  • Flood of March 1936

    The flood of March 1936 occurred in central and southern New Hampshire and affected the Saco, Connecticut, Merrimack, Androscoggin, and Piscataqua  Rivers. This flood event was caused by two separate rain events. The first rain event occurred from March 9-13 when 4 to 8 inches of rain fell in the foothills and mountains of Maine. The second rain event occurred from March 16-19 when another 4 inches to as much as 10 inches of rain fell. This rain fell on a "ripe" snowpack that melted quickly. The rivers still had a thick ice cover and as the ice was lifted and moved downstream bridges were damaged or destroyed. Large chunks of ice spilled out of the rivers banks along with the flood waters. The ice clogged streets and had to be removed by road crews. Flood damage costs were put at $25 million in 1936 dollars.

    flood city, water up to roof tops

  • Flood of September 1938

    The flood of September 1938 occurred when a hurricane struck New England after a week of almost continuous rain. The hurricane crossed Long Island, NY, and moved rapidly north on September 21, 1938. Prior to this hurricane there were several heavy rain events in New Hampshire. From September 17- 20 as much as 6 inches of rain fell from a large storm that moved through New England. This heavy rain caused the rivers in New Hampshire to be elevated and saturated the ground before the hurricane struck. The hurricane itself produced another 4-8 inches of rain in New Hampshire. The hardest hit river basins were the Connecticut, Pemigewasset, and Merrimack. Damage was estimated at $22 million in 1938 and there were 13 deaths.



  • Flood of November 3-4, 1927

    The flood of November 3-4, 1927, was caused by a tropical storm that produced 4-7+ inches of rain in New Hampshire. The ground was already thoroughly saturated by heavy rains that fell from October 18-21. This rain caused river levels to be elevated and filled all the lakes and ponds. The November 1927 flood is still the flood of record on the Connecticut River at West Lebanon, NH. The crest there was 35 feet, 17 feet above flood stage. Water covered the second stories of buildings along Main Street. There was 20 feet of water in Claremont. Many wooden bridges were destroyed as were miles of highway and railroad.  Damage costs were estimated at almost $20 million in 1927. There were no lives lost in New Hampshire.



  • Flood of April 2007

    The flood of April 2007 was caused by a strong coastal low pressure system that produced 4-8 inches of rain over a 3-day period resulting in rapid runoff and snowmelt. Damage to infrastructure was severe (roads, bridges, waste water treatment plants, public buildings). Homes and businesses were also damaged. Damage costs were $8 million but this was for public damage only. There were no deaths or injuries reported. Learn more.

  • Mother's Day Flood 2006

    The Mother's Day Flood 2006 occurred in central and southern New Hampshire. Low pressure developed south of New England and remained nearly stationary from the 12-15 resulting in more than 12 inches of rain in some locations in a 72-hour period. Homes and businesses were damaged extensively. Many roads were washed out and impassible. 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 because they were at risk for overflowing. Damage costs were $10 million but this is for public damage only. There were no deaths or injuries reported.



Flood Hazard Information
  • Flash Flooding

    Flash flooding is a rapid and extreme flow of high water into a normally dry area, or a rapid water level rise in a stream or creek above a predetermined flood level, beginning within six hours of the causative event (i.e., intense rainfall, dam failure, ice jam). More information...



  • River Flooding

    River flooding occurs when river levels rise and overflow their banks or the edges of their main channel and inundate areas that are normally dry. More information...
  • Tropical Systems and Coastal Flooding

    At any time of year, a storm from over the ocean can bring heavy precipitation to the U.S. coasts. Whether such a storm is tropical or not, prolonged periods of heavy precipitation can cause flooding in coastal areas, as well as further inland as the storm moves on shore. More information...

  • /Debris Flows

    Wildfires burn away the vegetation of an area, leaving behind bare ground that tends to repel water. When rain falls, it runs off a burn scar towards a low lying area, sometimes carrying branches, soil and other debris along with it. Without vegetation to hold the soil in place, flooding can produce mud and debris flows. More information...
  • Ice/Debris Jams

    A back-up of water into surrounding areas can occur when a river or stream is blocked by a build-up of ice or other debris. Debris Jam: A back-up of water into surrounding areas can occur when a river or stream is blocked by a build-up of debris. More information...
  • Snowmelt

    Flooding due to snowmelt most often occurs in the spring when rapidly warming temperatures quickly melt the snow. The water runs off the already saturated ground into nearby streams and rivers, causing them to rapidly rise and, in some cases, overflow their banks.More information...

  • Dam Breaks/Levee Failure

    A break or failure can occur with little to no warning. Most often they are caused by water overtopping the structure, excessive seepage through the surrounding ground, or a structural failure. More information...
Protect Life and Property NWS Forecast Offices and River Forecast Center (RFC) Covering New Hampshire