Areas of Major HeatRisk will persist for at least the Phoenix metro, Yuma, and El Centro through midweek before becoming widespread with areas of Extreme HeatRisk developing by Friday. The peak of this heatwave is likely to be Friday and Saturday with lower desert highs reaching 115-120°F. Little relief is expected at night with overnight lows mainly in the upper 80s and lower 90s to as high as the mid 90s by the weekend.