Santa Rosa's high of 106 degrees on Tuesday shattered a 79-year-old record, not that anyone who spent more than a few minutes outside needed convincing of that.
The hottest Sonoma County city, however, was Windsor, where a high of 109 left construction worker Brian Sheets withering in the sun, his faced streaked with sweat.
"Water, water, water," Sheets said, as he refilled a bottle in an air-conditioned mobile office at the Old Redwood Highway site before heading outside again.
Across the Bay Area, high temperatures eclipsed or came close to eclipsing long-standing records.
San Francisco's high of 98 torched the previous record of 89 and tied the highest temperature ever recorded for the month of August, according to the National Weather Service.
Napa and Kentfield in Marin County both hit 105, breaking records set in 1931. San Rafael's high of 100 also broke a record set in 1971.
Santa Rosa's high easily topped the city's previous record of 102 set in 1931, a year when more than one-third of the summer baked in 90 degree or higher temperatures.
The summer blast will be shortlived. After another hot one predicted for today, temperatures will begin to fall rapidly on Thursday and will reach only the high 70s this weekend.
"It's going to be a dramatic cool-down," said Duane Dykema, a Weather Service forecaster.
That will be welcome news for North Bay residents who had to curtail their outdoor activities Tuesday because of the heat.
In the Sonoma Valley, where the mercury reached 104 degrees, Glen Ellen resident Sam Avery and his Labradoodle, Buddy, had to wrap up their play time early at a dog park because of the intense afternoon heat.
"He's not moving too much," said Avery.
At the Windsor construction site, work was being done on the roof, adding another 20-30 degrees to the ground temperature, said John Williams, field superintendent for the 64-unit Burbank Housing project.
At lunchtime, the workers took refuge in the shade. Nick Garcia said he'd been on the roof multiple times Tuesday, stocking materials to prepare for the roofers.
Garcia put it simply. "It's really hot. We are taking turns."
Williams, a veteran construction worker said publicity in recent years about deaths of field hands from working in extreme temperatures has helped improve work-site education and conditions at many outside jobs.
Several large containers of water lined one wall of the office trailer, ready for use once the current container ran empty.
The cooler office was a respite if necessary, as well, said Williams. "We keep an eye on it."
Other high temperatures on the North Coast included:
Petaluma: 103
Rohnert Park: 106
Cloverdale: 108
Healdsburg: 105
Guerneville: 102
Bodega Bay: 71
In Mendocino County, Ukiah topped out at 106, five degrees cooler than the record set in 1932. In Lake County, the city of Lakeport reached the century mark.
Santa Rosa's high on Tuesday was 24 degrees higher than the average high of 82 degrees for that day in August.
Until Monday, Santa Rosa had been in the 90s just twice this summer. Both those days were in June.
In a typical summer, June 1 through the end of August, 16 days exceed are 90 or above.
Heat advisories Tuesday were issued by the Weather Service for much of the greater Bay Area.
Nationwide, the only other area with a heat advisory issued Tuesday morning was a swath of southeast Texas.
Petaluma's Fire Department opened its cool-down facility Monday and again Tuesday, offering a free location for anyone to go to get out of the heat with air conditioning and get some ice water.
On Thursday, Santa Rosa's high should be in the low 80s, a trend that will continue into the weekend with highs predicted to be in the upper 70s on Friday and Saturday.
Dykema said the forecast calls for average highs in the lower 80s early next week.
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