PHOENIX — Arizona is bracing for a sharp shift from summer heat to unsettled, cooler weather, with scattered storms expected this weekend and temperatures in Phoenix forecast to fall into the 70s by midweek. Friday, Oct. 9, is expected to be mostly sunny in Phoenix, with a high near 102 degrees. An isolated shower is possible in the High Country. The forecast calls for this to be the final triple-digit day of the stretch. Showers and thunderstorms could reach Phoenix and other parts of the state Saturday as a weather system off the California coast approaches and interacts with Tropical Storm Rachel. Saturday is expected to be cloudier, with a Phoenix high in the low 90s. Some storms may be light and widely spaced, but breezy conditions are expected in the lower deserts, with stronger winds in western and northern Arizona. The greatest storm threat is forecast for Sunday, when Rachel is expected to make landfall near the Southern California–northern Baja California border. Deeper moisture moving into Arizona could fuel more widespread showers and thunderstorms, some potentially strong or severe, with heavy rain and gusty winds. Northwestern Arizona is expected to see the heaviest rain bands, though strong storms could also affect Phoenix. The forecast cautions that dry air may limit rainfall in some areas, particularly parts of southern Arizona. Where heavier rain does fall, flash flooding is possible; damaging winds are also a concern. Storm activity around Phoenix may ease later Sunday and remain limited into Monday, although scattered showers could continue, especially in northern and western parts of the state. Another round of rain and storms is possible Monday night into Tuesday as the main weather system moves inland. Temperatures are forecast to drop along with the unsettled weather. Phoenix highs are expected to reach the mid-80s Sunday, the low 80s Monday and the upper 70s Tuesday and Wednesday. In northern Arizona, overnight temperatures next week could approach or fall below freezing. Winds may gust above 40 mph in northern Arizona Sunday, with breezy to windy conditions continuing into early next week. Residents in areas prone to flooding should be prepared for changing conditions during periods of heavy rain.