An early-season heat wave is poised to envelop the eastern United States from Monday through Thursday, heralding summer-like warmth for millions of residents. Temperatures are expected to climb into the 80s and 90s across the Southeast and mid-Atlantic regions, with cities such as Washington, D.C., potentially nearing record highs by midweek. While the presence of storms may temper the heat in portions of the Midwest and Northeast, areas that remain dry will experience the most intense warmth.