An unrelenting heat already frying California is threatening to send temperatures to record levels across the western U.S. this week, raising the risk of wildfires and propelling electricity prices to their highest levels since March.

Temperatures have already surged past 100 degrees Fahrenheit (38 degrees Celsius) in some parts of California, triggering heat advisories across the state. The dry, hot weather, combined with high winds, forced utility giant PG&E Corp. to shut off power to thousands of customers in northern California over the weekend to avoid the kind of catastrophic wildfires that broke out last year.

Wholesale electricity prices at a Northern California hub averaged $41.68 a megawatt-hour in the hour ended noon, almost double what they traded at in a day-ahead market and the highest level since March 11, power grid data compiled by Bloomberg show. While demand has risen as people blast air conditioners to keep cool, California’s grid manager said the state continues to have enough electricity on hand to handle the increase.

The heat is forecast to spread across other parts of the western U.S. later this week with temperatures in Seattle hitting a potential record as they approach 90 degrees on Wednesday, according to Accuweather. Portland could also see a high of 90 degrees on Tuesday and may approach a 1941 record of 95 for the date. Some areas of California were already seeing the highest or near-highest readings on Monday, according to the National Weather Service.

PG&E said overnight that it had restored power to most of the roughly 27,000 customers who were cut off over the weekend. The utility has warned in recent months that it plans to proactively shut service so its power lines don’t ignite wildfires when the weather is dry and the winds are strong.

Temperatures are forecast to drop in the San Francisco Bay area by Tuesday, but readings are expected to be above 100 degrees further inland.