State Climatologist Larry O'Neill said that while weak El Niños tend to be drier, very strong ones have historically brought more flood events. "We end up with more potential flood events during the very strong El Niños," O'Neill said.

The last three very strong El Niños — in 1982, 1997 and 2015 — were all wetter than normal in Oregon, according to O'Neill. However, he cautioned that "there's actually quite a wide range of outcomes here that we could expect."

Adam Batz, a meteorologist with the National Weather Service in Portland, echoed that uncertainty. "It's one of those things where we can't really say, 'Oh, it's gonna be a really bad flood season,' or 'It's gonna be well above average,'" Batz said.

Despite the uncertainty, state and federal agencies are preparing for the possibility of severe flooding. Low-lying areas along the Oregon Coast are particularly vulnerable, especially when heavy rain coincides with king tides — the highest tides of the year. The first king tides of the season begin Nov. 23.

Rhiannon Bezore of the Oregon Coastal Management Program said coastal flooding has already occurred this season and more is expected during storms. "Sometimes, when all of these things happen at the same time, you could just have these massive impacts on our coast," Bezore said.

Inland areas face risks as well. Warm temperatures combined with heavy rain could melt existing snowpack, leading to downstream flooding. "Some of Oregon's most severe flood events, especially in the Willamette Valley, have been associated with rain on snow events," O'Neill said.

Patence Winningham, deputy director of the Oregon Department of Emergency Management, warned that areas east of the Cascades could be hit hard because there is less vegetation to absorb excess water. She pointed to severe flooding in Harney County in 2025, where heavy rain and rapid snowmelt inundated roads and damaged homes.

Winningham also noted that drought-stricken and burn-scarred lands absorb water poorly, increasing the risk of landslides and debris flows. "We've burnt so much land in Oregon, the runoff could be significant," she said. Although the 2026 wildfire season saw fewer fires than usual, blazes still burned a record 2.1 million acres.

On the western side of the Cascades, several flood control dams can help hold back water, Winningham said. The Oregon Department of Emergency Management also operates a watch desk that monitors stream flows and forecasts to predict landslide risk. But she acknowledged that some areas lack infrastructure funding for levees and other protections.

Winningham urged residents, especially those in at-risk areas, to check whether their insurance covers flood damage. "Most homeowner's and renter's insurance policies do not cover flood damages," she said, recalling that many homes damaged in Harney County were trailers. "It goes back to our own individual preparedness on how we can care for ourselves and our families and our neighbors, and knowing what your hazards or risks are around your home."

While an increase in water supply could benefit the state's struggling reservoirs, the potential for flooding and landslides means communities must stay vigilant. Scientists and emergency officials agree that the coming months will require close monitoring and readiness for a range of scenarios.