Northern California heat wave almost over. Why has it been so hot in Sacramento?
Sacramento has set two daily heat records in the past four days, and could tie or break another one Tuesday afternoon with a 92-degree high in the forecast.
Recent temperatures from 93 degrees on Friday to 91 on Saturday are more than 15 degrees warmer than normal, according to National Weather Service data, which show the last week of April averaging daily highs between 74 and 76 degrees.
Even as temperatures cool in the capital city to about 85 by Wednesday and Thursday and the low 80s by the weekend, it’ll still mark a weeklong hot stretch that’s impacting most of Northern California, but especially the Sacramento Valley.
What’s the cause for this unseasonable heat?
It’s high pressure, a typical culprit for such heat waves that is also expected to bring drier weather and even more warm weather early next week after a weekend cooldown to near-normal temperatures, according to the weather service’s daily area forecast discussion posted online.
A “deeper trough,” or atmospheric pressure system, blowing in from the Gulf of Alaska will cool the valley to the low 80s by about Friday, according to the weather service.
“The good news is the heat will be short lived, with onshore flow developing by early evening as the ridge axis shifts eastward,” the weather service post said. “This will bring some cooling into Delta breeze influenced areas tonight.”
While the valley stays hot and dry, some light showers could fall in the north reaches of the state caused by a “shortwave” trough — a “disturbance in the mid or upper part of the atmosphere.” Showers could fall north of Interstate 80 and Shasta County.
Weather is hot, but water is cold
The weather service’s Sacramento office in social media posts since last week has warned that just because the weather outside is hot, does not mean it’s a suitable day to swim in a lake or river.
“It may be tempting to cool off near the river during these warm days, but area waterways are running very fast and cold due to mountain snow melt,” federal forecasters explained in a tweet.
This story was originally published April 28, 2020 at 11:23 AM.
