Scientists say that climate change, which has also contributed to the wildfires on the West Coast, helped intensify a storm that is unleashing a deluge in Florida, Alabama and Mississippi.

Scientists saw Sally’s stall over the warm waters of the Gulf as yet another effect of climate change in the United States, coming as wildfires along the West Coast have incinerated millions of acres and sent foul air into the atmosphere as far away as Washington, D.C. A scorching summer — made worse by the burning of fossil fuels, experts say — led to dry conditions that helped turn this year’s wildfires into the worst ever recorded.