A significant warmup is in the Rogue Valley forecast before a weekend cooldown that looks to include a decent amount of rain and some thunderstorms, the National Weather Service reported.

“It could be a bit of a washout this far in advance, but we have kind of a classic pattern for showers and thunderstorms coming in,” said National Weather Service meteorologist Ryan Sandler.

Temperatures this week are expected to be 15 to 20 degrees above the normal range of about 76 or 77 degrees, Sandler said. Medford is forecast to see a high temperature of 89 degrees Wednesday, followed by a high of 94 on Thursday and 93 on Friday.

The forecast has weather officials calling for a “moderate” heat risk for much of Jackson County. The Weather Service measures heat risk through an experimental system that has five levels of intensity, including, very low, low, moderate, high and very high. It looks at high and low temperatures and humidity in an effort to provide “a quick view of heat risk potential over the upcoming seven days,” according to the National Weather Service website.

“It works pretty well,” Sandler said. “I was a little skeptical when it first came out.”

On Saturday, the high is expected to plunge back to about 75 degrees. Around a half-inch of rain, with some lightning possible, is expected over the weekend.

“(Saturday) could be a wet day. We could have a steady rain for a while. It’s a big change,” Sandler said. “These look to be really wet storms.”