Hot or not? What forecasters expect for Northern California after looming heat wave
The blistering heat descending upon California over the next several days will propel temperatures throughout the Central Valley and Sierra Nevada foothills far above normal for July, including a 110-degree day in Sacramento’s forecast, before the weather system causing the swelter clears out.
But what’s in store for the rest of July?
Forecasts show a solid probability of Northern California temperatures cooling down from the impending heat wave after Sunday. A return to closer-to-normal temperatures is expected around the middle of next week, National Weather Service meteorologist Scott Rowe said.
However, after that, extended forecasts show a probability around 50% to 66% that temperatures will be at or warmer than average as the second half of July begins, Rowe said.
While that’s no guarantee of another big heat wave, he said, forecasters can detect high-pressure ridges that will create warming trends about a week-and-a-half in advance. Determining how hot those trends will get takes longer, which is why specific temperature readings are only given in short-term forecasts, not the long-term ones.
“Time is a big element in forecasting,” Rowe said.
The 50% to 66% probability range does suggest that a significant cooldown appears unlikely, Rowe said.
“Sometimes these climate outlooks are wrong,” he cautioned. “But the message to take home is that we’re not really gonna see much relief in terms of being below normal, at least in mid-July.”
The Sacramento metro area specifically, though, does get relief in the form of the Delta breeze, which he said will likely dilute this weekend’s heat wave starting Monday — a day or two before other parts of the valley start to cool down.
“Locally in California, that’s kind of our saving grace. It’s something places like Redding and Bakersfield don’t get to benefit from.”
The weekend heat wave inbound to California, which has prompted an excessive heat warning from the weather service from Friday through Monday, comes a result of a high-pressure ridge that originated in the Four Corners region — the intersection of Utah, Arizona, Colorado and New Mexico — and is migrating west, Rowe explained.
“The main culprit (in heat waves) is the large area of high pressure,” he said.
When California soared to record highs in mid-June, the cause was a similar high-pressure system that settled a little farther south of the current ridge.
Rowe said the main difference is that last month’s system rolled through earlier than normal, before the calendar start to summer, leading it to shatter records for that time of year. The current hot streak has to compete, historically speaking, with hotter post-July 4 records.
This story was originally published July 8, 2021 at 11:09 AM.
