Medford awoke to a view of Roxy Ann Peak Friday morning, a sight that had been hidden behind thick smoke from nearby wildfires for several days, and the air remained mostly clear through the day — at least compared with what residents have endured of late.

Medford awoke to a view of Roxy Ann Peak Friday morning, a sight that had been hidden behind thick smoke from nearby wildfires for several days, and the air remained mostly clear through the day — at least compared with what residents have endured of late.

"It was kind of nice to see the sun up instead of nothing," said National Weather Service meteorologist Chuck Glaser.

But weather officials cautioned people not to get too excited, predicting more smoke would roll in before long.

"It's probably going to be a temporary thing," said meteorologist Misty Duncan. "We're still going to have smoky conditions."

A low pressure system caused a shift in wind direction in the early-morning hours Friday, redirecting the breezes northward and pushing a sizable amount of the gray clouds out of the Rogue Valley.

The system also caused temperatures to plummet. Thursday's high temperature of 74 degrees was the city's the second-coolest high temperature for Aug. 1 in recorded history, according to the National Weather Service.

A video posted on the National Weather Service-Medford Facebook page Friday showed that weather officials expect the trend of some nighttime clearing in the Rogue Valley to continue for several days. During the daytime, smoke is expected to reaccumulate.

Smoke levels should remain fairly heavy in the Illinois Valley, and some may drift to the Curry County coast.

The smoke, coming from lightning-sparked wildfires in Josephine and Douglas counties that have torched more than 40,000 acres, has had a severe impact on regional air quality because of the fine particles in the smoke.

On Wednesday, Medford air was considered "hazardous," according Oregon Department of Environmental Quality, and it hovered in the "very unhealthy" category Thursday.

But on Friday it vacillated between "moderate" and "good" throughout the afternoon.

"It was a real pleasant surprise," said Byron Peterson, natural resource specialist for Oregon DEQ.

DEQ ratings are based on the number of fine particles in the smoke that can cause respiratory distress. A "moderate" reading shows the air quality is acceptable, but it could still affect a small number of sensitive people with respiratory conditions.

"Unhealthy" levels impact all groups. Grants Pass and Cave Junction remained in the red Friday, with an "unhealthy" reading throughout the day, DEQ data show.

Anything in excess of a 300 on the Air Quality Index is considered hazardous. Medford topped out at 344 Thursday, but that was practically clear skies compared with Merlin, which recorded a lung-choking index of 533.

Reach reporter Ryan Pfeil at 541-776-4468 or rpfeil@mailtribune.com.