Forecasters expect Southern Oregon temperatures to jump 10 to 20 degrees above average on Friday and Saturday, according to the National Weather Service office in Medford.

Readings in Medford, Shady Cove, Eagle Point, Grants Pass and other Rogue Valley cities could rise well into the upper 80s and will be more in line with early July than early May, forecasters wrote in a discussion posted to the NWS website. Ashland could see a high of 85 Saturday, according to forecasters. 

The forecast high for Thursday in Medford is 85 with sunny skies. Friday will see more sunny skies with a forecast high of 89, and it might hit 90 Saturday with clear skies, according to the weather service. Temperatures in Medford would drop to 87 Sunday and 83 Monday, NWS predicted.

Leading into the warm weekend, a strong Chetco effect is forecast for the Southern Oregon Coast near Brookings, NWS said. The Chetco effect will peak on Thursday, with highs in Brookings expected to reach the 80s Thursday afternoon — a few models even suggest 90 degrees is possible Thursday afternoon and perhaps Friday, as well, forecasters wrote.

“Friday afternoon looks to be the hottest places like North Bend and Roseburg,” according to the discussion.

“We aren’t too far from when the typical first 90-degree day of the year occurs in Medford (May 20th), and we do expect temperatures to adequately cool during the overnight hours, so any impacts should be brief,” forecasters wrote.

Residents are advised to be aware of the sudden warmup and take precautions.

“Take it easy if working/recreating outdoors over the next few days,” the discussion said. “If you plan to seek relief in the area’s waterways, remember that these water sources are fed by snowmelt and the water is COLD. Wear a life jacket and take frequent breaks from the cold water to warm up. Don’t forget about pets … they need shade and water too, and please please never leave children unattended in a closed vehicle!”