Tropical Depression Nine has formed in the Atlantic and forecasters believe it could intensify into the season's first hurricane before reaching the US Gulf Coast. The National Hurricane Center says the system could strengthen rapidly in the Gulf. AccuWeather and The Weather Channel are also monitoring Tropical Storm Isaias, which is developing on a similar path toward the coast.

Separately, an AccuWeather heat advisory remains active for inland areas near San Francisco until 10 p.m. Thursday. Coastal areas are left out of the warning.