- 1900: Cable exchange of weather warnings and other weather information begins with Europe.
September, 1900: A devastating hurricane strikes Galveston, Texas, killing more than 6,000 people. The wife of the Galveston Official-in-Charge Isaac Cline and one Weather Bureau employee and his wife are killed in the associated flooding. The Weather Bureau forecasts the storm four days earlier, but not the high tide.
- 1901: Official three-day forecasts begin for the North Atlantic.
At the Weather Bureau Conference in Milwaukee, Wis., Chief Willis Moore observed the Post Office Department was delivering slips of paper with daily forecasts, frost and cold-wave warnings, to everyone's door with the mail. The one disadvantage to the system was the mail carriers started their routes about 7:00 a.m. and that day's forecast was not issued until 10:00 a.m., so the previous night's forecasts were used.
- 1902: The Marconi Company begins broadcasting Weather Bureau forecasts by wireless telegraphy to Cunard Line steamers.
The Weather Bureau begins collecting flood damage statistics nationally.
- 1903: Weather sensitive historic events: United States and Panama sign the Canal Treaty; the first automobile trip across the United States is completed from San Francisco to New York City; The Wright brothers make first powered airplane flight at Kill Devil Hill, N.C., after consultation with the Weather Bureau several years earlier for a suitable location to conduct their experiments.
- 1904: The government begins using airplanes to conduct upper air atmospheric research.
- 1905: The SS New York transmits the first wireless weather report received on ship at sea.
- 1907: Weather sensitive historic event: Round-the-world cruise of U.S. "Great White Fleet" including 16 battleships and 12,000 men.
- 1909: The Weather Bureau begins its program of free-rising balloon observations.
- 1910: Weather Bureau begins issuing generalized weekly forecasts for agricultural planning; its River and Flood Division begins assessment of water available each season for irrigating the West.
- 1911: The first transcontinental airplane flight, from New York City to Pasadena, Calif., by C.P. Rogers, in 87 hours and 4 minutes, air time, over a period of 18 days.
- 1912: As a result of the Titanic disaster, an international ice patrol is established, conducted by the Coast Guard; first fire weather forecast issued.
- 1913: Professor Charles F. Marvin serves as the new chief of the Weather Bureau, replacing Professor Moore. Marvin serves until his retirement in 1934.
- 1914: An aerological section is established within the Weather Bureau to meet growing needs of aviation; first daily radiotelegraphy broadcast of agricultural forecasts by the University of North Dakota.
- 1916: A Fire Weather Service is established, with all district forecast centers authorized to issue fire weather forecasts.
The Weather Bureau's fire district forecast center started at Medford, Oregon.
- 1917: Norwegian meteorologists begin experimenting with air mass analysis techniques which will revolutionize the practice of meteorology.
- 1918: The Weather Bureau begins issuing bulletins and forecasts for domestic military flights and for new air mail routes.
- 1919: Navy Aerological Service established on a permanent basis.
First Transatlantic flight by U.S. Navy sea plane, with stops in Newfoundland, Azores and Lisbon.