Oregon is forecast to see some wild weather swings between very wet and very hot over the coming week as summer gets underway with a bang.

‘Atmospheric river’ to hammer valley, mountains

The National Weather Service expects 1 to 1.5 inches of rain in the Willamette Valley, and 2 to 3 inches in the mountains, from Sunday into Tuesday. Upward of 4 inches could fall in parts of the Columbia River Gorge.

NWS meteorologist Daniel Hartsock said the amount of rain was unusual for early June and was coming from an “atmospheric river” of moisture off the Pacific Ocean. Typically, the Willamette Valley gets about 1.5 to 1.7 inches of rain for the entire month of June.

“It’s definitely unusual to get a month’s worth of rain in two days, but it’s also not unheard of,” he said. “We’ve had one or two day periods like this in the past, but I wouldn’t say it happens very often.”

Major heatwave could hit 90 or even 100 degrees

The weather is set to dry out and warm up by midweek, and then temperatures are forecast to rise rapidly.

Hartsock said Friday brought the best chance to see 90 degree weather in western Oregon, and there was even a 10% chance of temperatures cracking 100. The forecast could change over the coming week, but chances appear very likely to bring the warmest temperatures of the season by next weekend.

“I’d say that east of the Cascades we have an even better chance of really warm temperatures,” Hartsock said.

Zach Urness has been an outdoors reporter in Oregon for 16 years and is host of the Explore Oregon Podcast. Urness is the author of “Best Hikes with Kids: Oregon” and “Hiking Southern Oregon.” He can be reached at zurness@StatesmanJournal.com or (503) 399-6801. Find him on X at @ZachsORoutdoors.