Posted September 6, 2010, 11:30 PM.

Last week, the inland valleys experienced scorching heat, some of the worst of the summer. Saturday was the hottest day of the sequence, slightly hotter than Friday in most locations, with Lake Elsinore recording 109°F, Wildomar and Murrieta 108°F, Menifee and Hemet 107°F, Temecula 106°F, Moreno Valley and French Valley 105°F, Riverside and Perris 104°F, and De Luz at 100°F.

Triple digit heat ended at the county line, however; Fallbrook (in San Diego County) registered a high of 92°F Saturday.

The coming week will feature temperatures in the 70's and 80's, with the warmest locations coming in only in the lower to middle 80's.

Two low pressure troughs will be responsible for the drop, the second one lodging itself off the west coast and staying there a while. Onshore flow will help push a deep marine layer well into the inland valleys.

And, according to the Climate Prediction Center, the cooler weather is in for extended run - for at least the next two weeks.