Heat Wave Grips US Southwest, Expected to Intensify Later This Week

Strong High-Pressure System Blankets a Wide Area

A persistent heat wave is currently gripping a broad swath of the western and southern United States.

Low-pressure systems are positioned far to the north — one near Ontario, Canada, and another around Kansas in the central US — keeping them well clear of the affected region. Meanwhile, a powerful high-pressure system has anchored itself over central Mexico, extending its influence across the entire southern United States.

How the "Heat Dome" Is Pushing Temperatures to Extremes

What makes this heat wave particularly severe is the presence of an upper-level ridge of high pressure — commonly known as a "heat dome."

When an upper-level high extends prominently above its surroundings, air beneath it is forced downward and compressed, causing temperatures to rise. The high-pressure system also promotes persistent clear skies near the surface, allowing intense solar radiation to heat the ground directly. The combination of strong insolation and adiabatic warming from atmospheric compression is producing record-breaking heat across a vast area.

Major Airport High Temperature Forecasts (July 31 – August 2)

Phoenix and Las Vegas, both situated in desert terrain, are expected to see temperatures exceeding 100°F for multiple consecutive days, making them the epicenter of this heat event. Dallas, Texas is forecast to reach 109°F on Friday. By contrast, Los Angeles along the California coast remains comparatively mild at around 84°F, sheltered by cool marine breezes off the Pacific — a striking contrast to conditions inland.

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