Monsoon season begins soon. Here's everything you need to know

Arizona’s monsoon season officially begins June 15 and runs through September 30, bringing a shift in wind patterns that delivers much-needed rainfall and temporary relief from scorching summer temperatures. The National Weather Service has designated Monsoon Awareness Week to highlight both the benefits and dangers of the season, which include flash flooding, debris flows, lightning, downbursts, and dust storms. Forecasts suggest above-normal precipitation across the state, with a 30-40% chance for most regions and nearly 50% in northeastern Arizona, though odds remain close to normal levels. The monsoon results from a seasonal wind pattern change, where high-pressure systems shift northward, drawing moisture from the Gulf of California and other southern water bodies. This creates daily cycles of rising hot air over land, pulling in cooler, moisture-laden air from the sea—a process similar to a sea breeze. The Climate Prediction Center notes that while rainfall won’t be evenly distributed, the monsoon typically accounts for 30-60% of Arizona’s annual precipitation. Record-low snowpack from last winter may accelerate monsoon impacts, as bare ground heats up faster, allowing high-pressure systems to shift northward earlier. Additionally, El Niño—a warming of Pacific Ocean waters—could enhance moisture from tropical cyclones, increasing rainfall chances. However, the scattered nature of monsoon storms means some areas may still face drought conditions despite the overall positive outlook. Residents are advised to prepare for sudden downpours, which can lead to flash flooding and debris flows, particularly in dry riverbeds. The National Weather Service emphasizes staying informed through weather alerts and avoiding unnecessary outdoor activities during severe storms. While the monsoon offers relief from extreme heat, its unpredictability requires caution to mitigate risks.