SONOMA COUNTY, Calif. (KTVU) - SAN FRANCISCO (KTVU) -- The National Weather Service has issued an Excessive Heat Watch for the weekend because of soaring temperatures that could hit triple digits for parts of the Bay Area.
The watch is in effect from 11 a.m. Saturday through 11 p.m. Monday, when temperatures are expected to be 20 degrees above normal across a wide swath of the region.
KTVU chief meteorologist Bill Martin said a high pressure system is building over Northern California, which will allow the mercury to soar.
The hottest temperatures of the year happen to coincide with a three-day music festival in Sonoma County.
Country Summer drew about 10,000 people to the fairgrounds in Santa Rosa Friday afternoon, with at least that many fans expected on both Saturday and Sunday as well.
By the time headliner Thomas Rhett took the stage at 8:15 p.m., the temperature was down to 85 degrees, but it peaked earlier in the day at 98.
That was a full 26 degrees higher than the Sunday before, when an unseasonably cold storm brought rain and hail to the North Bay.
"As we say in the business, it's better to be warm than wet," executive producer Alan Jacoby told KTVU.
"Rain is no good. This is actually great weather. We start watching it a month in advance."
Country Summer brings 14 acts to multiple stages.
"It feels really hot and our seats are right in the sun," lamented fan Michele Tripp, who traveled from
Sacramento, and expected Santa Rosa to be cooler.
Tripp and companion Gary Rains sought out an air-conditioned hospitality room, available to upgraded ticket holders.
"We go out, listen to a few songs, start sweating, and then come in here, to cool off and hydrate, then go back out for more," said Rains.
Fans used spray bottles, ice, moistened towels, and hats to stay cool.
Shaded areas were crowded, and many people brought umbrellas to create their own canopy.
The rapid spike in temperature makes it feel even hotter.
"People aren't really acclimated to it, so we've really been trying to stress the need to hydrate," said Santa Rosa Assistant Fire Marshal Paul Lowenthal, who was walking the grounds inspecting the event.
"It's hot out here. Fortunately we've got a little bit of wind. But it's only going to get hotter throughout the weekend."
To help the breeze, several huge fans were positioned on the perimeter, creating a 40-50 mph wind.
With water hoses attached, they sprayed a cooling mist over the crowd.
The fans are normally used to keep frost off wine grapes.
"Usually they're sitting in the middle of a vineyard to protect the grapes," explained Chris Hale of Belkorp AG, who supplied the fans.
"We came up with a creative idea to cool the crowd, a giant squirt gun!"
Medical staff was standing by for any fans overcome by heat.
"I don't even remember walking in here," admitted Rachel Cohn of Petaluma, who was treated for heat exhaustion late in the afternoon.
Cohn said she had a few drinks and food, after hours sitting in the sun, and suddenly she felt nauseous. Her friend noticed Cohn was confused, and couldn't complete a sentence.
"I tried to get water on her and cool her off," Lauren Huntley of Petaluma told KTVU.
"No matter what we did, shade, water, nothing would cool her off so we had to get her in here."
Cohn had never suffered heat-related illness in her life, but thinks she was close to passing out.
"I remember being in the shade. I remember parts of walking here. But I don't remember laying down. I don't remember the paramedics talking to me."
Country Summer is in its fourth year, and has grown bigger every year.
"Sunscreen and water, beer and country music, that's it," smiled fan Megan Jensen of San Francisco, " I mean, what else could we need?"