Severe heat continues to build in Arizona and across the Southwest, with conditions in Phoenix threatening to become the city’s longest heat wave on record, according to the National Weather Service. The long-lived heat wave in the Southwest comes on the heels of a hot June that included several weeks of dangerously hot temperatures and humidity in Texas and across the South. Forecasts show that the ongoing heat wave will continue to scorch the Southwest this week and into next week, and will expand across the southern portion of the United States.