As a heat wave bore down on the state this week under a dome of high pressure centered over the Desert Southwest, the state\u2019s grid faced its first stress of the summer season. On July 5, consumption exceeded the grid operator\u2019s forecast. CAISO expected a 44,595 MW demand, but in late afternoon consumption reached 44,775 MW. First, the heat wave sent temperatures soaring well above 100 degrees in inland valleys and desert areas\u2014from Redding in Pacific Gas & Electric territory to the suburbs of Los Angeles in areas served by Southern California Edison and the Los Angeles Department of Water & Power. Near-record setting heat in some areas sent power demand and use electric-powered cooling devices into overdrive. \u201cWe are urging our customers to look at ways they can save energy,\u201d said Ron Deaton, LADWP general manager, July 3. Governor Arnold Schwarzenegger responded by ordering the state Office of Emergency Services to open 13 \u201ccooling centers\u201d on county fairgrounds to provide shelter for heat sensitive individuals without air conditioning. He ordered state agencies, including the California Independent System Operator, to help notify people of the availability of shelters. The office will coordinate activities to help residents facing severe heat throughout the summer, said Henry Renteria, office director. The state put together a hot weather emergency response plan after last summer\u2019s heat storm (Circuit, Aug. 4, 2006). The all time record peak demand for the California ISO is 50,270 megawatts set on July 24 last year. On July 5, demand exceeded forecast. The grid operator expected customers to use 44,595 MW during peak hours. However, users pulled 44,775 MW out of the system that evening. In a strange twist, prices stayed relatively calm, not exceeding $70\/MWh by much during the most heated and constrained parts of the week, and staying in the $40\/MWh to $50\/MWh much of the time. Things remained hot in California on July 5, but the weather was expected to cool over the weekend, according to the National Weather Service. The strain on the grid started July 3 when a fatal small plane crash in San Diego County clipped two high-voltage transmission lines as it took off from McClellan-Palomar airport in Carlsbad. Two people were killed. Also in San Diego County, there were temporary shutdowns of three power plant units. NRG Energy\u2019s 963-MW plant in San Diego County went offline July 3 due to equipment failures, but by later in the week the company had brought most of its 12 units back online, with the rest expected to be restored by the end of the week. Meanwhile, the Southern California Edison-operated San Onofre nuclear power plant went back online June 29 after being shut down nine days earlier for repairs. The 1,070-MW plant was operating at two percent capacity upon reopening, but was back up to full capacity by Independence Day. Also during the week, San Diego Gas & Electric partially shut its 550 MW Palomar Energy Center in Escondido for planned maintenance, resulting in a temporary capacity crimp of 50 MW. PG&E\u2019s Helms Pumped Storage 400 MW unit 3 was also down for the count.