A “Heat Dome” Could Send Portland Temperatures to 110 Degrees Next Week

A weather forecasting model predicts temperatures cresting above 100 degrees Fahrenheit in Portland this coming weekend, and blistering heat reaching 120 degrees in Oregon east of the Cascades.

The National Weather Service says that might happen. Or it might not. Either way, it’s going to be hot as hell in Oregon this week.

“The signal we’re getting this year is very strong that it will be hot,” says John Bumgardner, a meteorologist with the National Weather Service’s Portland office. “We have reasonable confidence that we will hit 100 in many places, but how hot it will get is uncertain at this time range.”

The model that attracted horrified rubberneckers on Twitter is developed by the European Centre for Medium-Range Weather Forecasts, an independent intergovernmental organization funded by 34 nations.

It’s predicting a “heat dome” settling over much of the Pacific Northwest this week. That’s a ridge of high pressure that allows hot air to build in a vertical column, and limits clouds from forming.

The model shows that dome settling over Northeastern Oregon this week, and sending temperatures soaring across the state by Sunday, June 27. The model shows Portland temperatures hitting 110 degrees—that’s not a typo, one hundred ten degrees—on Tuesday, June 29.

The National Weather Services uses the model to make its forecasts. But Bumgardner says it’s difficult to rely on forecasts a week in advance.

“We’re hesitant to forecast anything quite that hot,” he says. “If that happens, it’s possible we could see a state record. But uncertainty is still pretty high that far out in time.”

Bumgardner points to last summer, when temperatures were expected to reach 100 degrees, but were held down by wildfire smoke clouding out the sun. Reason for hope!