At least two people have died and more than a dozen remain missing following severe flash flooding in the Grand Canyon area over this past weekend. Officials continue search efforts amid concerns about the lingering threat posed by heavy rain in northern Arizona and surrounding regions.

Meteorologists attribute the intense flooding to a combination of factors linked to extreme weather patterns. The Southwest’s ongoing drought, unusually warm ocean temperatures, and the influence of a strong El Niño event have all contributed to elevating moisture levels in the atmosphere, intensifying the region’s typical monsoon activity. Arizona’s monsoon season, which runs from mid-June through late September, regularly brings thunderstorms and heavy rain, but this weekend’s rainfall was notably extreme.

Chad Merrill, a senior meteorologist, explained that El Niño has driven higher-than-normal sea surface temperatures in the eastern equatorial Pacific, increasing atmospheric moisture. Additionally, a marine heat wave spanning from Southern California to Hawaii raised dew points and humidity across the region, further energizing storms. Randy Cerveny, a meteorologist with Arizona State University, noted that the Grand Canyon’s unique topography, with its high elevation on the South Rim, generates strong uplift forces that fuel convective thunderstorms. While such storms are common during the summer, this event’s intensity was exceptional.

Conditions on the ground exacerbated the flooding’s impact. Persistent drought and a recent burn scar left by a wildfire diminished soil absorption capacity, causing heavy rainfall to rapidly run off the steep, rocky terrain into canyons and waterways below. Near the flood’s epicenter, gauges recorded 1.24 inches of rain in three hours, including nearly an inch in a single hour, intensifying runoff and flash flood potential.

Weather forecasters warned that the combination of elevated atmospheric moisture and regional weather dynamics created a high risk for continued flooding through the weekend and into the coming days. Flood watches extended from Arizona into Utah and western Colorado as moisture-laden storms remained active. The National Weather Service in Flagstaff cautioned that flash flooding could occur in normally dry washes, side canyons, swimming holes, and low-water crossings, posing dangerous conditions to residents and visitors.

Adding to concerns, meteorologists are monitoring the possible approach of a tropical storm or hurricane remnant near California in the coming week. While many models predict the system will move into open waters without making landfall, some suggest that its moisture could still contribute to increased precipitation in the Intermountain West. This potential further rainfall highlights how warm Pacific sea surface temperatures are creating an environment conducive to extreme weather events in the western United States.

The convergence of long-term drought, elevated ocean temperatures, El Niño-driven moisture, and regional topographic features underscores the complexity behind this weekend’s deadly flooding and signals ongoing vulnerability to such natural hazards in the Southwest.