Kennewick is weird. If you’re coming from Seattle, you probably expect the usual Washington gray—that misty, bone-chilling drizzle that defines the Pacific Northwest. But cross the Cascades and everything changes. You aren’t in the "Evergreen State" anymore. Honestly, you’re in a high-desert shrub-steppe that feels more like Nevada than Western Washington.
The weather in Kennewick WA is defined by a massive rain shadow. The mountains basically grab all the moisture from the Pacific and squeeze it out before it ever reaches the Tri-Cities. What’s left for Kennewick? About seven to nine inches of rain a year. That is almost nothing. To put that in perspective, Seattle gets about 38 inches. You're living in a place that gets less than a quarter of the rain of its famous neighbor.
Why the Summer Heat Isn't What You Think
People hear "desert" and they panic about the heat. And yeah, it gets hot. July highs average around $92°F$ or $93°F$, and hitting triple digits is a regular occurrence. But there is a secret: it’s dry.
Humidity in the summer stays incredibly low, often dipping into the 40% range or lower. You don't get that sticky, "I can't breathe" feeling you find in the South. Instead, it’s a crisp heat. The moment the sun dips behind the Horse Heaven Hills, the temperature craters. It’s common to see a $30°F$ or $40°F$ swing between lunch and midnight. You’ll be sweating at the Columbia Park boat races at 2:00 PM and reaching for a hoodie by 9:00 PM.
The sun is relentless here. Kennewick clocks in about 300 days of sunshine a year. If you struggle with Seasonal Affective Disorder, this is your sanctuary. June, July, and August are basically wall-to-wall blue skies.
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The Winter Reality of the Tri-Cities
Winter in Kennewick is a bit of a gamble. Most years, it’s just cold and brown. You’ll see average highs in the low 40s and lows in the high 20s. Snow isn't a guarantee like it is in Spokane. Some years, the city gets maybe an inch or two that melts by noon.
But then, every once in a while, the "Artic Blast" hits.
Because there aren't many trees or hills to block the wind coming down the Columbia River Gorge, the wind chill can be brutal. Kennewick’s record low is a bone-shattering $-21°F$ from back in 1985. While that's rare, don't be shocked if you wake up to a "silver thaw"—that nasty freezing rain that coats everything in a quarter-inch of ice. It’s worse than snow. It shuts the city down.
Wind: The Constant Companion
If you’re moving here, buy a heavy-duty grill cover. Seriously. Kennewick is breezy. April is technically the windiest month, averaging about 12 mph, but gusts of 30 or 40 mph happen whenever a front moves through.
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The wind is actually why the wine here is so good. The Horse Heaven Hills to the south create these pressure differentials that keep the air moving. This prevents frost from settling on the grapes and toughens the skins, which is why the Cabernet Sauvignon from this region is world-class. If you can handle your patio furniture moving across the yard once a month, the trade-off is some of the best wine on the planet.
When Should You Actually Visit?
Most locals will tell you that May and September are the "sweet spots."
In May, the desert is actually green for a few weeks before the summer sun bakes it brown. The temperatures are usually in the 70s—perfect for hiking Badger Mountain. September is similar, with the added bonus of the harvest season and the smoke from regional wildfires usually clearing out.
Speaking of smoke, that's a real factor now. Late August can sometimes be "smoke season" if there are fires in the Cascades or Canada. The bowl-like geography of the Tri-Cities can trap that air, making it hazy for a week or two. It sucks, but it’s the reality of the modern West.
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Essential Survival Tips for Kennewick Weather:
- Hydrate constantly. The dry air wicks moisture off your skin before you even realize you're sweating.
- Sunscreen is non-negotiable. With nearly 3,000 hours of sunshine a year, you will burn in twenty minutes at the river.
- Dress in layers. Even in the middle of summer, a night at a Tri-City Dust Devils game can get surprisingly chilly.
- Check the wind forecast. If it says 20+ mph, maybe don't take the boat out on the Columbia; it gets choppier than you’d expect.
What This Means for Your Trip
Kennewick isn't just a stopover; it's a climate anomaly. You get the warmth of the desert with the power of the Columbia River running right through the middle. It makes for a lifestyle that’s built around being outside—golfing in February (which people actually do here) or paddleboarding in July. Just don't expect to see a lot of umbrellas. Most people here don't even own one.
If you’re planning a move or a visit, your best bet is to embrace the dry. Pack your sunglasses, leave the raincoat at home, and be ready for a lot of blue sky.
Actionable Next Steps:
- Check the 10-day forecast specifically for wind gusts if you plan on being on the water.
- Pack a high-SPF sunscreen regardless of the season—the high-altitude desert sun is stronger than it looks.
- Book tee times or outdoor reservations for May or September to experience the most temperate "Goldilocks" weather the region offers.