Regional Weather
Desert Southwest Monsoon Guide: Flash Floods, Dust Storms, Lightning, and Heat
A Southwest monsoon guide covering flash floods, dust storms, lightning, dry washes, heat bursts, and rapidly changing desert weather.
Quick answer: The Southwest monsoon brings seasonal moisture that can trigger thunderstorms, flash floods, dust storms, lightning, and sudden wind.
Moisture surge
Moisture moving into desert regions can fuel thunderstorms over mountains, valleys, and cities.
Storm coverage can vary sharply day to day.
Flash floods
Dry washes, slot canyons, underpasses, and burn scars can flood quickly even from distant rain.
Water can arrive before rain falls overhead.
Dust and lightning
Outflow winds can create dust walls and dangerous crosswinds.
Lightning can strike far from the rain core.