September 20, 1909 Tsunami: Grand Isle, Louisiana, United States
A tsunami of meteorological origin began at Grand Isle, Louisiana, United States on September 20, 1909. Its effects were recorded at 1 place. It killed 300 people.
Where the waves reached
The source (white) and every runup with a place, colored by the water height recorded there. A ring is a runup NCEI marks doubtful.
- Under 1 m
- 1 to 3 m
- 3 to 10 m
- 10 to 30 m
- 30 m and more
- Height not recorded
The tsunami
- Date
- September 20, 1909
- Source
- Grand Isle, Louisiana, United States
- Cause
- Meteorological
- Runups recorded
- 1
- Waters
- Ocean
- How certain
- Erroneous entry
The toll
- Deaths
- 300
Where the literature gives no number, NCEI records a description on a scale of 1 to 4, printed here in its words. Damage is in millions of US dollars of the year of the event, not adjusted for inflation.
What the record says
NCEI’s account, from the sources it cites.
Not a tsunami, but a storm surge. This date correlates with the Grand Isle Hurricane, which formed over Hispaniola on September 13th and made landfall at Berwick, Louisiana on September 20, 1909. The hurricane devastated Grand Isle. There was 15 foot storm surge that inundated much of southern Louisiana (Reference #1804). The hurricane headed inland in path between New Orleans and Baton Rouge. The confusion is related to a newspaper article appearing in the Elizabeth Daily Journal, New Jersey, on September 22, 1909 (Reference #1803), which stated "The tidal wave followed the gale and storm which had been sweeping the coast for several days. The waves swept along the coast just as the gale was dying away and the people were beginning to think their troubles were over. There was no chance to escape, as the wall of water burst upon the little villages along the coast and swept everything before." The article was based on the stories of refugees from the storm who arrived in New Orleans.
Every runup
Nearest the source first. Heights are above sea level at the time; a tide gauge reads half the wave’s full height.
| Where | Country | Km from source | Water height, m | Inland, m | Measured by | First wave, UTC | Deaths |
|---|---|---|---|---|---|---|---|
| Grand Isle, LA, LA | United States | Eyewitness observation of water height | 300 |
More
Every tsunami in 1909The 1900sTsunamis of United StatesThis day in weather historyAlerts in force
Sources
Tsunami events and runups from NOAA’s National Centers for Environmental Information, Global Historical Hazard Database, cited as NCEI/WDS, doi:10.7289/V5PN93H7. Public domain. Read 2026-09-24. NCEI tsunami event 2370.