California narrowly averted rolling blackouts Sunday night to relieve strain on its electric grid as parts of the state suffered record-breaking temperatures.

The California Independent System Operator, which operates much of the state’s electric grid, had anticipated a 4,000-megawatt power-supply shortage, driven in part by import constraints and wildfires affecting transmission lines in parts of the state. It called a Stage 2 emergency, urging utility customers to conserve power during the early evening hours, but stopped short of calling for rotating outages.

An extreme heat wave in the Southern half of the state sent temperatures in some areas above 120 degrees, forcing residents to shelter inside and crank their air-conditioning units, boosting electricity demand. As a result, the grid operator’s power-reserve margins wore thin at several points throughout the evening as solar generation began to decline.

Californians responded by conserving energy during the supply crunch, and the grid operator called off the emergency Sunday evening.

In addition to the heat threat, parts of the state may also face power outages throughout the week due to an expected windstorm. On Saturday, PG&E Corp., which serves 16 million people in Northern and Central California, said it may pre-emptively cut power to about 103,000 customers in 17 counties starting Monday to reduce the risk that its electric equipment could spark wildfires.