Supported forecasts indicate more than 100 million Americans will face triple-digit temperatures later this week, marking the second such event in a month, with prior peaks of 116°F in Phoenix and 110°F in Utah and Montana. The heat dome is shifting eastward, with Northeast highs including up to 101°F in the Washington D.C. area expected Wednesday and Thursday. Unverified projections of widespread new records, particularly overnight lows, remain under discussion.