Hurricane Hilary was a powerful Pacific hurricane in August 2023 that unleashed torrential rain and mudslides across Mexico's Baja California peninsula and the U.S. Southwest. Forming on August 16, it rapidly intensified into a Category 4 storm with 140 mph winds by August 18, before making landfall as a tropical storm in San Quintín, Mexico on August 20. The storm prompted the National Hurricane Center to issue its first-ever tropical storm warning for Southern California, affecting roughly 26 million people across Arizona, California, Nevada, and Utah. The hurricane caused 3 deaths and $48 million in damage in Mexico, while in the U.S. it led to 1 death and $900 million in damage, with Death Valley National Park closing for a record two months due to damaged roads. Hilary broke rainfall records in four U.S. states, with some Southern California areas receiving up to 600% of their typical August rainfall, leading to widespread flooding and power outages.