when did it strike the first country?
Late September 2018
Hurricane Rosa (2018)
Hurricane Rosa brought widespread flooding to northwestern Mexico and the Southwestern United States in late September 2018, 
where did hurricane rosa hit? Northwestern Mexico and the Southwestern United States
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Hurricane Rosa (2018) [SEP] Introduction
Hurricane Rosa brought widespread flooding to northwestern Mexico and the Southwestern United States in late September 2018, and was the first tropical cyclone to make landfall in Baja California since Nora in 1997. The seventeenth named storm, tenth hurricane, and seventh major hurricane of the 2018 Pacific hurricane season, Rosa originated from an Atlantic tropical wave that crossed the West African coast on September6. The wave proceeded westward across the Atlantic, traversing Central America before entering the Gulf of Tehuantepec on September 22. There, the weather system acquired cyclonic features and became a tropical storm on September 25. Within a favorable atmosphere, Rosa entered a period of rapid intensification on September 27, peaking as a Category4 hurricane with maximum sustained winds of 150 mph (240 km/h) a day later.