Crank up the AC.

Crank up the AC.

Temperatures across the Rogue Valley are expected to spike Tuesday, with some parts — Medford included — crossing the scorching 100-degree threshold.

"We're nearing the hottest time of the year just in terms of seasonal norms," said meteorologist Shad Keene of the National Weather Service. But Medford's typical July 1 temperature is about 86 degrees, making Tuesday's predicted high of 103 degrees 17 degrees above normal.

Ashland, parts of Northern California and the Illinois Valley are also expected to reach 100 degrees or hotter.

Keene said a mass of high pressure has continued to build across the U.S., resulting in the temperature increases. Weather officials noted the triple-digit climbs still won't touch the high-temperature record for July 1 — 108 degrees — set in 1942.

The climb will be short-lived, though it may not feel that way to most. Medford highs for the rest of the week through Friday will remain in the mid- to low-90s.

Keene said the hot weather comes with an increased chance for thunderstorm activity. A chance of lightning strikes over the Siskiyous and parts of the Cascades is predicted for Tuesday and Wednesday.

"(Hot weather) just kind of sets the stage for thunderstorms sometimes, and this is no different," Keene said.

— Ryan Pfeil