Oregon climatologist says severe ice storms to occur more often in future despite rising temps

PORTLAND, Ore. (KOIN) — The effects of climate change are expected to bring more freezing rain and severe ice storms to the Willamette Valley, the foothills of the Cascades and the Columbia River Gorge in the next 50 to 75 years, according to the 2025 Oregon Climate Assessment.

The ice storms are expected to result from a 5-degree increase in Oregon’s average temperature by 2074, and a 7.6-degree increase by 2100. Oregon State University Climatologist Larry O’Neill told KOIN 6 that scientists were surprised to discover that warmer temperatures could result in an increased rate of severe ice storms in the Willamette Valley.

“We started a simple question: Will freezing rain decrease?” O’Neill said. "It’s very natural to think that would be the case. What we found, actually, is that big impactful ice storms may increase in the future.”

The rising temperatures are expected to cause fewer minor ice storms, O’Neill said. However, warmer temperatures are also forecast to bring more rain to the region and create stronger low-level, easterly winds in the Columbia River Gorge. These easterly winds bring cold air to the Columbia River Gorge, the Willamette Valley, and the foothills of the Cascades. The combination of the added rainfall and the stronger easterly winds are projected to result in a higher rate of severe ice storms when temperatures drop to freezing or near-freezing levels.

“Projections suggest that easterly winds through the Columbia River Gorge may strengthen during winter, even as the Willamette Basin becomes warmer,” the climate report reads. “Therefore, ice accretion on some surfaces in the region may increase during freezing rain events.”

These severe ice storms could have major impacts on the region’s infrastructure. Concerned about the future of the region’s electrical grid, Portland General Electric joined local researchers in a 2023 study, which focused on the causes and effects of the potential increase in wind-driven freezing rains in the Willamette Valley.

“Ice accretion from freezing rain can damage power and communication lines, housing, and other infrastructure; disrupt and endanger air and ground transportation, and harm plants and animals,” the report reads.

The results of these studies may serve as a guide for local businesses and government officials planning for the future.

“Portland General Electric was hoping for less [freezing rain],” O’Neill said. “[The study] has actually influenced some of their decisions on things like infrastructure. There are a lot of big decisions to make … the power infrastructure is not designed for what we’re anticipating in the future. Infrastructures will have to be prepared for hot and cold extremes.”