Hottest September day ever? Brutal heat to reach Sacramento area before Labor Day
If the hottest August ever recorded wasn’t quite enough for you, how about some record-shattering September heat?
Labor Day weekend in Northern California will be, in a word, hot. In two words: Extremely hot.
The National Weather Service predicts a high of 110 degrees Sunday in Sacramento, which would obliterate an all-time record of 103 degrees for that date, set in 1958.
A 110-degree high would also top that of Sept. 1, 2017, which was the capital’s hottest September day of all time at 109 degrees, according to the NWS.
Forecasters expect Friday to stay in the mid-90s before Saturday reaches about 101 degrees. Sunday’s swelter will subside only slightly, with the Labor Day holiday Monday also expected to soar to 107, also breaking a daily record. Tuesday’s forecast high is 101 degrees.
The NWS has issued an excessive heat watch Saturday through Tuesday for a majority of the northern half of the state, including all of the Sacramento Valley, parts of the greater Bay Area and along most of the North Coast. Highs throughout the valley and foothills are expected to range from 95 to 110 degrees, and will vary from 75 to 100 degrees near the mountains.
The NWS on Thursday morning also posted a map showing that a “very high heat risk” will be present throughout the valley, and urged people to avoid outdoor physical activity if possible and hydrate frequently.
Emily Heller, a NWS meteorologist, said earlier this week an area of high pressure would settle over the valley later in the week.
Heller said dense smoke from wildfires that continue to burn across Northern California could lower temperatures in some areas.
But near-surface smoke and wildfire air pollution have eased considerably in recent days near the capital region. As of 7 a.m. Thursday, you could still see some haze on the horizon, but the air quality index in downtown Sacramento was at an AQI reading of just 38, according to local air district website SpareTheAir.com.
An AQI between 0 and 50 marks ideal air quality; Wednesday’s readings stayed in the range from 51 to 100, which is deemed “moderate.” Spare The Air predicts AQI levels below 115 in Sacramento, Yolo, Solano and El Dorado counties both Thursday and Friday. Any AQI level between 101 and 150 is classified as “unhealthy for sensitive groups,” such as those with asthma, children or those who are pregnant, but still relatively manageable for the general public.
“Wednesday through Friday, light to moderate onshore winds will aid pollutant dispersion in the Sacramento area,” the forecast page on SpareTheAir.com said.
That outlook can change if there’s a significant flare-up in wildfire activity, producing more smoke. One day last month, amid the intense August heat wave, the NWS predicted a high for Sacramento Executive Airport of well over 100 degrees; it ended up reaching just 88 degrees because smoke from the LNU Lightning Complex wildfire blocked out sunlight for much of the day, the NWS said.
Was last month really Sacramento’s hottest August ever?
Yes, quite easily.
The NWS posted a calendar breakdown of last month’s temperatures to social media. Downtown Sacramento hit above-average temperatures 28 of the 31 days, reaching triple digits 13 times. Aug. 15 reached 111 degrees and Aug. 16 hit 112. Both were records; the latter marked Sacramento’s hottest August day ever.
One day, Aug. 20, was near average with a max of 92 degrees. Just two days, Aug. 5-6, were cooler than average, the NWS said.
In total, the average daily max temperature downtown was 98.4 degrees last month, more than six degrees hotter than average and breaking a record of 97.8 degrees set in 1967. Nighttime lows averaged 66.2 degrees for the month, almost 5 degrees warmer than average, breaking a record of 64.3 set in 2019.
This story was originally published September 3, 2020 at 7:52 AM.
