September came in like a lion in California and much of the west with plenty of heat across the region.  The California daily composite temperature marched up quickly to 80 degrees and held there through the first 9 days of the month.  The heat even extended down into Southern California which has mostly stayed cooler compared to the rest of the state so far this summer.  Soon thereafter, however, temperatures dipped by 10+ degrees and stayed depressed for the final two thirds of the month.  This meant a decrease in load within CAISO compared to July and August, averaging 28.9 GW (down 2 GW from the previous month).  Even with the below-normal temperatures, load still stayed ahead of September the previous year when it sat at just 26.6 GW through the full 30 days. 

Figure 1. California Daily Average Temperature and Difference from Normal (F)