Rain in Washington is about as surprising as coffee in Seattle. We get it. But rain in August? That’s usually the one month where we can actually plan a wedding or a hike without a "Plan B" involving tarps and Gore-Tex.
Then came August 2025.
Basically, the skies opened up in a way that left even the most seasoned meteorologists at the University of Washington scratching their heads. We aren’t talking about a few localized thunderstorms or a "marine layer" drizzle. This was an honest-to-god atmospheric river—a phenomenon we usually reserve for the dark, soggy days of November—crashing the summer party.
That Weird August 14 Atmospheric River
If you were on the Olympic Peninsula or near the North Cascades in mid-August 2025, you know exactly what I’m talking about. It was loud. It was heavy. And it was incredibly rare.
On August 14, 2025, a Level 3 atmospheric river (AR 3) made landfall. For context, the scale only goes to 5. Seeing an AR 3 in August is like seeing a snowplow in July; it just feels out of place. This system wasn't a fluke. It was a massive plume of moisture stretching all the way back to the Western Pacific, fueled by sea surface temperatures that were way warmer than they should’ve been.
By the time the clouds cleared on August 16, spots on the windward slopes of the Olympics had swallowed 3 to 6 inches of rain. Some isolated gauges in the Cascades even nudged toward 8 inches.
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The numbers are kind of staggering for a month that usually sees less than an inch of rain total.
Why We Didn't All Float Away
You’d think 8 inches of rain would cause a catastrophe. Normally, it would. If this had happened in January, the Skagit River would have been in everyone’s living rooms.
But August is different.
The ground was bone-dry. Before the rain hit, Washington was actually staring down a pretty serious drought. The soil acted like a giant, thirsty sponge, soaking up the initial deluge before it could turn into a wall of runoff. According to the Washington State Climate Office, this "antecedent dryness" is the only reason we weren't dealing with widespread 2021-style flooding.
Still, it wasn't all sunshine and rainbows.
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- Bellingham saw 148% of its normal August rainfall in just two days.
- Hoquiam got hit with 152% of its monthly average.
- Omak—which is usually a desert this time of year—saw a massive 296% of its normal rain thanks to convective thunderstorms piggybacking on the moisture.
The "Summer Rain" Myth vs. Reality
There’s a common misconception that Washington summers are getting wetter. Honestly, the data says the exact opposite. Long-term trends analyzed by the State Climatologist, Karin Bumbaco, show that our summers are actually getting drier and hotter on average.
So why the heavy rain?
It’s about volatility. We’re seeing more "all or nothing" weather. We go weeks with zero precipitation, and then a single, super-charged event drops a month’s worth of water in 48 hours. Scientists call this "precipitation whiplash." It’s a hallmark of a warming atmosphere—warmer air can hold about 7% more water vapor for every degree Celsius of warming.
When that moisture-laden air hits the mountains, it’s like squeezing a wet towel. You get everything at once.
What This Means for Your Backyard
If you’re a gardener, you probably cheered. Your lawn finally stopped looking like shredded wheat. But for the state’s infrastructure, these summer bursts are a nightmare.
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Wildfire burn scars are particularly vulnerable. When heavy rain hits a recently burned area, there are no roots to hold the soil. The water just slides off, carrying ash and debris with it. We saw some of this localized "muck" moving in the eastern Cascades, though thankfully nothing that blocked I-90 for long.
Also, think about the salmon. While the extra water helped cool down some of the smaller creeks, the sudden surge can also wash out nests or bring in a ton of urban runoff—basically a cocktail of oil and tire dust from the roads—which isn't great for the fish.
How to Handle Future Summer Deluges
We can't really treat August like a "safe" month anymore. If you live in Western Washington, you’ve basically got to stay "storm-ready" year-round now.
- Clear those gutters early. Don't wait until October. If a summer AR is in the forecast, five minutes of clearing leaves can save you a flooded basement.
- Watch the burn scars. If you're hiking or camping near an area that burned in the last two years, get out of there if heavy rain starts. Flash floods in those zones happen in seconds.
- Check your drainage. Ensure your yard slopes away from your foundation. Summer soil can be so hard and compacted that water just bounces off it and finds the nearest crack in your concrete.
- Monitor the NWAC and NWS. The National Weather Service in Seattle and Portland are getting much better at spotting these summer plumes early. If they mention "subtropical moisture" or an "IVT over 500," grab your raincoat.
Washington state August heavy rainfall is no longer a freak occurrence; it's a part of our new, weirder seasonal cycle. Stay dry out there.
Actionable Next Steps:
Check your local flood zone maps via the FEMA Flood Map Service Center to see if your property’s risk profile has changed with recent terrain shifts. If you live near a recent wildfire area, sign up for your county’s emergency "Reverse 911" alerts to get instant notifications about potential debris flows.