Remnants of Tropical Storm Mario Bring Heavy Rain, Flooding, and Power Outages to Imperial Valley

Imperial Valley, CA — September 18, 2025

The remnants of Tropical Storm Mario swept into Southern California on Thursday, unleashing widespread rainfall and triggering significant impacts across the Imperial Valley.

Around 5 p.m., a cluster of thunderstorms developed over southern portions of the valley and just south of Mexicali, Baja California. Within 30 minutes, the storms organized into a strong northward-moving line, producing torrential downpours and damaging winds.

The severe weather toppled power lines, forcing road closures and leaving thousands of residents without electricity. Low-lying areas across the valley quickly filled with water, with several neighborhoods reporting extensive flooding.

According to the National Weather Service office in Phoenix, between one and one-and-a-half inches of rain fell across central portions of the valley in a short period, prompting flash flooding.

The impacts came as little surprise. A day earlier, the NWS issued a flood watch for the region, citing the threat of excessive rainfall. The Storm Prediction Center also outlined a marginal risk for severe weather, warning of the potential for isolated tornadoes and strong thunderstorms.

As cleanup begins, residents are urged to remain cautious around flooded roadways and downed power lines while crews work to restore services and repair damage.