A vast plume of Saharan dust, roughly the size of the continental United States, crossed the Atlantic towards the Caribbean and US Gulf Coast. It matters because it can make skies hazy, reduce air quality and alter local summer weather, while its dry air may also inhibit the development of tropical storms and hurricanes.

The plume travelled more than 5,000 miles from North Africa and was expected to affect areas from Florida to Texas after already reaching Puerto Rico and the Caribbean. Saharan dust outbreaks are a regular warm-season phenomenon: the dust is carried high in the atmosphere by winds, can suppress rainfall and thunderstorms, and may be most troublesome for people with respiratory conditions when concentrations near ground level are high.