Oregon’s Big Fall Rains Are Here. What’s Really Going On Up There?

This past weekend, the Oregon skies opened up in a big way, with some regions receiving nearly 5" of rain from Friday to Sunday. Streets shimmered, rivers surged, and it felt like fall arrived overnight. This wasn’t your usual drizzle, it was the kind of steady, soaking rain that signals Oregon’s rainy season has officially begun.

But what actually causes these intense bursts of rainfall that seem to appear out of nowhere? The answer lies high above us, in something scientists call an atmospheric river, sometimes nicknamed a river in the sky.

What Is an Atmospheric River?

Imagine a long, flowing current of moisture moving through the atmosphere, thousands of miles long and hundreds of miles wide carrying as much water as some of Earth’s largest rivers.

These atmospheric rivers form over warm parts of the Pacific Ocean, then drift eastward with the jet stream until they reach the Pacific Northwest. When that moisture-laden air collides with Oregon’s Coast Range and Cascade Mountains, it cools, condenses, and releases that stored-up water as rain.

That’s why a single weather system can turn a calm day into a multi-day downpour, and why Oregon’s forests, rivers, and waterfalls look so vibrant afterward.

Why Oregon Feels It So Much

Oregon is perfectly positioned to catch these “sky rivers.” The Pacific’s storm track points almost directly at the state, making western Oregon one of the wettest regions in the continental U.S.

Here’s how that plays out across the map:

• Oregon Coast Range: Some areas receive over 100 inches of rain a year — nearly ten times what falls in parts of eastern Oregon.

• Willamette Valley (Eugene, Corvallis, Salem): Typically sees 40–50 inches annually, enough to keep the farmland, vineyards, and forests thriving.

• East of the Cascades: Once you cross the mountains, the air dries dramatically. Bend and Redmond average under 15 inches a year, with wide-open blue skies and big temperature swings.

  
  

That contrast — from mossy forest to desert plateau in a matter of hours — is part of what makes Oregon such an incredible place to explore.

How to Dress for Oregon’s Rainy Season

The secret to enjoying Oregon’s fall and winter weather is simple: prepare, don’t hide. With the right gear, you can stay comfortable and still make the most of every day outdoors.

A few tried-and-true tips:

• Wear a lightweight waterproof jacket with a hood and breathable lining.

• Choose waterproof shoes or hiking boots — puddles are part of the fun.

• Dress in layers — Oregon’s weather shifts quickly from rain to sun.

• Skip the umbrella — coastal breezes and Gorge winds make them more hassle than help.

• Pack a warm hat and gloves for mountain or coast adventures.

And don’t forget: the days after heavy rain are some of the most stunning in Oregon. Waterfalls roar, the air smells clean and earthy, and the sunlight glows through the mist like a painting.

Embrace the Weather, It’s Part of Oregon’s Story

Atmospheric rivers are more than a meteorological curiosity — they’re part of the natural rhythm that shapes Oregon’s landscapes. They feed the rivers, replenish reservoirs, and keep the state’s forests lush and alive.

Instead of avoiding the rain, embrace it. It’s when Oregon reveals some of its best magic — from fog curling through vineyards to the thundering power of Silver Falls or the coastal cliffs after a storm.

With Best Oregon Tours, you can experience Oregon’s beauty in every season — rain or shine. Our guided Oregon day trips are designed for comfort, curiosity, and connection, helping you explore what many believe to be one of the most diverse eco systems on the planet.

Book your next adventure today, and see why even a rainy day in Oregon can be unforgettable.