Can rain quench Oregon’s drought ahead of fire season?

PORTLAND, Ore. (KOIN) — With much of Oregon in a state of moderate drought or worse, the region will need more than the recent rounds of rain and snow to tame this year’s fire season, experts say. 

Oregon state climatologist Larry O'Neill told KOIN 6 News that dry winter and spring seasons have historically led to harsher wildfire seasons, and for much of Oregon, the winter months have been abnormally dry. So dry, O'Neill said, that about 75% of Oregon has received less than 75% of its normal precipitation since October 1.

“Because we have experienced such a dry winter, an active wildfire season this summer is still a very open possibility,” O'Neill said.

National Weather Service Hydrologist Andy Bryant told KOIN 6 that the recent rounds of rain and snow should have a measurable impact on the region’s drought conditions. However, it’s difficult to predict what Oregon’s drought status will look like leading up to wildfire season.

“The upcoming rain should help, but it's difficult to assess how much until it occurs,” Bryant said. “For western Oregon, especially in the Coast Range and Cascade foothills, there are rainfall deficits of 5 to 20 inches just for the past 90 days, not to mention the water year or multi-year deficits, nor to address the precipitation, soil moisture, and reservoir storage deficits east of the Cascades.”

Because the region is dealing with both long-term and short-term drought, Bryant said that Oreogn will need multiple seasons of above-average precipitation to see substantial long-term drought improvement. Drought conditions in Western Oregon are less dire than those in the central and eastern parts of the state. However, with winter winding down, Western Oregon will need another wet spring in order to evade more serious drought conditions heading into wildfire season.

While rainfall has been mild, the region’s abnormally cold winter temperatures have helped to maintain a healthy seasonal snowpack. As a result, the near-normal snowpack is expected to delay wildfire season into mid-summer for areas above 5,000 feet of elevation.

“Fortunately, since high elevations have mostly been below freezing this winter, we have been able to keep a hold of the snow that fell,” O'Neill said. “So, despite the large precipitation deficits, the near-normal snowpack is very much helping minimize drought severity and extent in Western Oregon. Because of this, a wetter-than-normal spring would absolutely improve drought severity in Western and Northern Oregon.”

Based on historical precipitation and temperature patterns, O’neill said that the Willamette Valley has a 24% chance of complete drought recovery by this summer. However, it’s more likely that the region will be in some stage of drought during the summer of 2023.