A natural El Nino, human-caused climate change, a stubborn heat dome over the nation’s midsection and other factors cooked up Tropical Storm Hilary’s record-breaking slosh into California and Nevada, scientists figure. Cooked up is the key phrase, since hot water and hot air were crucial in rapidly growing Hilary and then steering the storm on an unusual path that dumped 10 months of rain in a single weekend in normally bone-dry places. Nearly a foot of rain fell in parts of Southern California’s mountains, while cities smashed summertime records. 

Related articles: 

• The Guardian: What role did the climate crisis play in Storm Hilary – and could there be more like it? 
• Vox: Hurricane Hilary is the latest in California’s unusual weather patterns
• Mother Jones: How heat-shattering ocean temperatures impacts fisheries