​Crespi is back on the practice field as it looks to keep up its momentum in 2026 after a 10-1 season. (Eric Sondheimer / Los Angeles Times)In a sign of how high school football practices in Southern California have changed over the last 20 years, Crespi athletic director Brian Bilek was holding a beeping device on Monday to determine what modifications might be needed to practice in heat. It was 100 degrees in Encino, but the reading from the wet-bulb device measuring heat and humidity gave out a number that allowed for practice to take place with precautionary measures.This is the most important duty for athletic trainer or athletic director right now. It’s reading the Wet Bulb. Crespi’s Brian Bilek gives a tutorial. pic.twitter.com/MGtPYblgzu— eric sondheimer (@latsondheimer) July 27, 2026Southern Section players were in shorts and wearing helmets around the Southland. City Section teams began five days of mandatory acclimation periods to get players into shape.It’s an annual ritual that once had programs practicing twice or even three times a day. CIF rules that restrict tackling to two days per week and a maximum of 45 to 90 minutes a day were adopted in an effort to protect players from concussions and injuries.By the weekend, when the shoulder pads come on, coaches will be breaking out in smiles watching their freshmen players trying to figure out the routine for the first time.Crespi coach Brad Vonnahme grew up in the Central Valley and coached at Fresno State. He described the weather from those days as “toasty.” Monday’s environment, though, was probably the hottest opening day in his four seasons at Crespi.It’s a big year for the Celts. They’ve improved each season after Vonnahme was put in charge of a rebuilding project following Crespi’s 0-10 season in 2022. The Celts have responded with records of 2-8 and 5-6 before their 10-1 mark last season. This year, they’ve upgraded their schedule, adding rival Sherman Oaks Notre Dame for a season-opening nonleague game Aug. 21. Asked if his team can continue to climb, Vonnahme said, “I think we can. But most importantly, we have to try. Everybody wants us to continue to elevate.”Crespi’s Russell White carries the ball during a game against St. John Bosco on Nov. 7, 1986. (John McCoy / Los Angeles Times)This season marks 40 years since Crespi’s greatest team, led by running back Russell White, won the Division 1 championship over St. John Bosco in 1986. It remains the only San Fernando Valley team to win a Division 1 football title. Many of the players are expected to attend the Notre Dame game for a recognition ceremony.Crespi returns a number of players who were standouts as sophomores, led by quarterback Chase Curren. They’ll need to be bigger, faster and stronger. If all goes well, they will play Salesian on Oct. 30 to decide the Del Rey League title.A strong group of teams will be traveling to Hawaii next month, so they’ll be getting ready a little faster