California Power Grid Tested as Heat Soars

California's power grid operator extended its call for consumers to conserve electricity into Thursday as a heat wave continued to bake the state, especially the inland cities.

Electricity supplies statewide were expected to be tight as consumers cranked up their air conditioners, the California Independent System Operator (ISO) said in a statement.

The ISO said it was also dealing with power plant outages, reductions in transmission line capacity and the possibility of limited imports because of high temperatures in neighboring states.

The ISO forecast that demand would reach 46,888 megawatts on Thursday and 46,274 MW on Friday as some inland cities like Sacramento and Fresno top out at around 110 degrees Fahrenheit (43 Celsius).

On Wednesday, demand peaked at 45,790 MW, the highest so far in the 2016 summer season. Though high, that fell short of 2015's 47,358-MW peak set in September and the grid's all-time record of 50,270 MW set in July 2006.

To help maintain grid reliability, the ISO on Wednesday told electric companies to restrict maintenance on generating facilities and transmission lines. The ISO has not yet restricted maintenance for Thursday.

Restricting maintenance and issuing so-called flex alerts for conservation are among the first of many steps the ISO can take to maintain reliability during high demand or other stresses to the system.

AccuWeather forecast temperatures in the biggest cities along the coast, like Los Angeles, San Diego and San Jose, would top out in the 80s F on Thursday and Friday. Highs in San Francisco are expected to reach the 70s F over the next week.

State agencies in April warned that millions of electric customers in Southern California could suffer power outages of up to 14 days this summer due to the limited availability of Southern California Gas' Aliso Canyon gas storage facility after it shut due to a massive methane leak in October.

SoCalGas, a unit of Sempra Energy (SRE), said on its website that gas supplies should be enough to meet demand this week.

The company expects to deliver over 3.4 billion cubic feet of fuel on Thursday and almost 3.4 bcf on Friday, with 2.8 bcf coming from pipelines and 0.5-0.6 bcf from storage facilities.

If correct, Thursday's deliveries would be the highest for SoCalGas so far this summer. (Reporting by Scott DiSavino