As temperatures across Sonoma County and the North Coast climbed near triple digits Friday, 7-year-old David Kranz of Santa Rosa headed straight for Ridgway Swim Center’s kiddie pool and its giant blue mushroom that cascades cool liquid relief onto frolicking youngsters.

“It sprays water and it’s fun,” he said. “It’s my favorite.”

A heat wave gripped the region Friday, forcing many residents to seek the comfort of local rivers, lakes, beaches and pools. The combination of a ridge of high pressure and the lack of coastal breeze pushed the mercury to 97 degrees in Santa Rosa. Though Friday was the second-hottest day of the year — temperatures hit 100 on June 8 — Friday fell well short of the all-time high for July 25. It was 105 degrees on July 25, 1975.

“Winds are light offshore, which eliminates the ocean effect,” said Larry Smith, a meteorologist with the National Weather Service.

An onshore breeze is expected to cool the region starting Saturday, Smith said, bringing temperatures into the mid-80s through the weekend, just in time for a full lineup of summer events, including Saturday’s Vineman Triathlon and the Sonoma County Fair that runs until Aug. 10.

Friday’s stagnant air and high temperatures prompted Bay Area air quality officials to declare a Spare the Air alert, urging people to cut back on any activities that cause pollution such as driving, using oil-based paints, gasoline-powered lawn mowers and household aerosol products like hair sprays. An alert was not in effect for Saturday.

Sonoma County’s Emergency Services department was monitoring the weather, but did not open cooling centers, said Zach Hamill, an emergency coordinator. He said temperatures would have to climb into the 100s or stay hot for three or more days to trigger an emergency response.

“This isn’t something out of the ordinary for Sonoma County in the summer,” he said.

To beat the heat, many residents headed to Sonoma County beaches on Friday, according to Meda Freeman, Sonoma County Regional Parks spokeswoman. Popular spots included Spring Lake’s swimming lagoon, which hosted 500 swimmers on Friday, public beaches along the Russian River and Doran Beach at Bodega Bay.

“Doran Beach is one of the most popular beaches on a hot day,” she said. “It’s always going to be cooler at the coast.”

Nicole Green of Santa Rosa cooled off with a swirl of vanilla and chocolate soft serve ice cream from Foster’s Freeze on Fourth Street.

“It’s an ice cream kind of day,” she said. “It feels good. Really good.”

Both of Santa Rosa’s public swim centers, Finley and Ridgway, were at capacity Friday afternoon, according to Don Hicks, recreation supervisor. Attendants at Ridgway, with its slide and water features, were turning swimmers away after 380 packed into the pool.

“The slide is a big draw with kids, especially on a hot day like today,” he said.

David Kranz’s mother, Kim Kranz said she and her three children got to the pool an hour before it opened to ensure they got a spot. She compared the facility to a water park in Windsor that closed in 2006.

“I remember Windsor Waterworks,” she said. “This is the next best thing. I heard it was going to be in the 90s and I wanted to get the kids out of the house.”