Arizona mornings still feel comfortable across the Valley right now, but the desert heat is already building. Sunshine and calm winds will dominate the Phoenix metro through the early week, setting the stage for an unusually intense burst of spring heat.
Sidewalks warm quickly under clear skies, and that warming trend accelerates day by day.
According to the National Weather Service in Phoenix, an Extreme Heat Watch is in effect from Thursday morning through Sunday evening across south-central Arizona. Afternoon highs are expected to reach between 103°F and 109°F, temperatures well above normal for mid-March.
Cities across the metro including Phoenix, Glendale, Mesa, Tempe, Chandler, and Scottsdale could see triple-digit heat during the afternoon hours later this week.
The heat will build steadily first. Temperatures climb from around 90°F today to the mid-90s by Tuesday, then approach 101°F by Wednesday before the most intense heat arrives.
Meteorologists say this pattern is tied to a strengthening upper-level ridge expanding across the Southwest.
For residents and visitors enjoying Spring Break or St. Patrick’s Day events, hydration and sun protection will be essential. Outdoor workers and hikers in areas like South Mountain, Camelback Mountain, and the Superstition foothills should plan early morning activities and avoid peak afternoon heat.
Heat-related illnesses can develop quickly when temperatures exceed 100 degrees, especially during strenuous outdoor activity.
Light clothing, frequent water breaks, and shaded rest periods will help reduce risk. Vehicles parked in direct sun will heat rapidly as well.
The heat wave is expected to persist into the weekend before any meaningful cooling arrives.
Five Day Outlook for Phoenix, Arizona
Sunday: Sunny and warm. High near 90°F.
Monday: Sunny and mild. High near 91°F.
Tuesday – St. Patrick’s Day: Sunny and hotter. High near 96°F.
Wednesday: Sunny and hot. High near 101°F.
Thursday: Sunny with extreme heat building. High near 104°F.
