Southern California’s blazing heat wave is expected to begin slowly cooling down on Wednesday, Oct. 25 but not before breaking records – possibly even a century-old one.

Coastal areas in Orange County will have it the best, the National Weather Service reported; they were expected to cool down to the lower- to mid-70s. The inland areas will hit the mid-80s to lower-90s before cooling toward the weekend.

In Riverside County, temperatures were expected to hover around the lower-90s through Saturday.

The story is much the same in Los Angeles County, where many spots can expect to stay in the lower- to mid-90s through the weekend – much cooler than Tuesday’s peak, but still well above average.

A preliminary report had Lake Elsinore at 101 degrees on Tuesday, which would break its previous high of 100 degrees for the calendar day set in 1903. The city of Riverside wasn’t far behind – it didn’t break its record of 101 set in 1909, but did come in at 99 degrees.

In Orange County, Newport Beach felt a record early.

By 6 a.m. Tuesday, it was 85 degrees, easily the hottest day on record for the city – which later in the day reached 92 degrees, the National Weather Service reported.

The heat wave is being caused by multiple factors working together, the National Weather Service said. A dome of high pressure sitting over the western United States has mixed with Santa Ana winds blowing in warm air – either would raise temperatures on its own, but put them together and you get this week’s heat wave.

Brett Albright, a meteorologist with the National Weather Service, said Tuesday was likely the worst of it, but it’s going to be a slow slide back down to normal temperatures, with above-average heat continuing through the weekend.

“Stay hydrated,” he said. “If you can limit your outdoor activities to the early morning and evening hours, that also helps. It’s tricky – in dry heat, people don’t sweat as much, so they don’t necessarily notice they’re getting dehydrated.”