The United States National Hurricane Research Project drops eight cylinders of silver iodide into the eyewall of Hurricane Esther. Wind speed reduces by 10%, giving rise to Project Stormfury.

Hurricane Esther was the first large tropical cyclone to be discovered by satellite imagery. The fifth tropical cyclone, named storm, and hurricane of the 1961 Atlantic hurricane season, Esther developed from an area of disturbed weather hundreds of miles west-southwest of the southernmost Cape Verde Islands on September 10. Moving northwestward, the depression strengthened into Tropical Storm Esther on September 11, before reaching hurricane intensity on the following day. Early on September 13, Esther curved westward and deepened into a major hurricane. The storm remained a Category 3 hurricane for about four days and gradually moved in a west-northwestward direction. Late on September 17, Esther strengthened into a Category 5 hurricane with sustained winds of 160 mph (260 km/h) on September 18. The storm curved north-northeastward on September 19, while offshore of North Carolina. Esther began to weaken while approaching New England and fell to Category 3 intensity on September 21. The storm turned eastward early on the following day, and rapidly weakened to a tropical storm.