A scorching heat wave bearing down on San Diego County will cover most of California for nearly a week but — at least for now — the state’s electric grid is holding up and there are no indications that power shutoffs are coming.
“It’s definitely going to be hot but it’s looking like the grid will be stable throughout the heat wave,” said Anne Gonzales, senior public information officer for the California Independent System Operator, which manages the flow of electricity across the high-voltage power lines for about 80 percent of the state, plus a small part of Nevada.
After months of cooler and wetter than usual weather, the first real blast of hot weather is enveloping the San Diego area. The National Weather Service has issued an excessive heat warning for the mountains, deserts and valleys through 8 p.m. Tuesday.
The story is similar throughout California.
“There’s a lot of excessive heat warnings, as well as heat advisories, basically covering the entire state of California away from the immediate coastline and into some mountain locations,” said Elizabeth Adams, meteorologist for the weather service in San Diego. “And it also looks like Nevada and Arizona are almost completely covered.”
In Sacramento, where forecasters predict a high of 106 degrees Friday and 110 for Saturday, the California State Fair canceled horse races out of concern for animal safety.
Hot weather puts stress on the state’s electric grid, as homeowners and businesses crank up their air conditioners.
Last year, a similar “heat dome” that blanketed California and neighboring states in late August through early September led the system operator, known as the CAISO for short, to issue a record 10 consecutive days of Flex Alerts — that is, requests for utility customers to voluntarily reduce consumption in the late afternoon and early evening hours.
Flex Alerts are sent out when demand on the grid threatens to outpace the available megawatts needed to keep the power system running smoothly.
At the height of last year’s 10-day run of Flex Alerts, demand on the system hit a single-day record of 52,061 megawatts on Sept. 6.
For perspective, demand Thursday was projected to peak at 38,884 megawatts, while capacity on the CAISO system was projected at 50,640 megawatts.
“No supply shortages are anticipated, and we have no Flex Alerts or emergency declarations planned at this time either,” Gonzales said. “We are closely monitoring and we’re encouraging Californians to stay vigilant in case grid conditions change.”
Different than Flex Alerts, Public Safety Power Shutoffs can be implemented to cut power to specific, targeted areas, especially in the backcountry. Called PSPS for short, they are used by California utilities to reduce the risk of power lines falling and igniting a wildfire when the weather is hot, dry and windy.
Fortunately, the heat wave in the San Diego area has not been accompanied by gusty winds and on Thursday, San Diego Gas & Electric’s Weather Center reported the outlook for the next seven days does not warrant issuing a PSPS.
The National Weather Service expects the hot weather to continue at least into the middle of next week, with temperatures in areas more than 5 miles from San Diego’s coast rising into the 90s.
“The highest temperatures for our forecast area are going to occur on Saturday and Sunday,” Adams said. “We have the potential for high temperatures in the lower desert to reach 118 to 123 degrees.”
The average high this time of year in Borrego Springs is 108 but the desert community is forecast to hit 119 degrees Saturday. That would break the previous record for that particular day of 117, set in 2006.
To make matters worse, evening temperatures are expected to be warmer than usual. The lower deserts, for instance, can expect overnight lows between 84 to 94 degrees.
“That’s going to exacerbate the heat risk because you usually see some heat relief overnight with temperatures falling but with this event that’s just not really going to happen,” Adams said. “Temperatures are going to remain very hot overnight.”
During an excessive heat warning, the weather service advises drinking plenty of water, checking up on relatives and neighbors and never leaving children and pets in a vehicle unattended. If you do go outside, the NWS suggests wearing loose-fitting clothes and schedule strenuous activities in the early morning or evening.
