A brief spell of hotter-than-normal weather will persist on Friday, with some areas experiencing near-heatwave conditions and possible haze. Light, localized rain may occur mainly in the east. On Saturday, a significant cooling trend will begin as thunderstorms and widespread showers spread across the country, raising the risk of flash floods in desert regions. The cooler, unsettled weather will continue into Sunday and Monday, with further drops in temperature, brisk winds, and scattered showers, especially in the north and along the coast.