Summer in Seattle is a total lie. Or at least, the version of it you’ve seen on postcards is. Everyone talks about the "Big Dark"—those nine months where the sky is the color of a wet sidewalk—but nobody warns you about the absolute whiplash of July.
Honestly, the summer in seattle weather is less of a season and more of a collective sigh of relief that sometimes turns into a panic when the thermometer hits 90 degrees. You’ve probably heard it’s always raining here. It isn't. Not in July. In fact, Seattle often gets less rain in the summer than Miami or New York City. We actually go through these weird, mini-droughts where the grass turns that crunchy, toasted-yellow color and everyone starts eyeing their neighbor’s sprinkler with suspicion.
The "June Gloom" is a Real Vibe
If you book a flight for the first week of June, you’re playing a dangerous game. Locals call it "June Gloom." The marine layer—a thick, stubborn blanket of clouds from the Pacific—likes to park itself over the Puget Sound and just... stay there.
It’s not cold, exactly. It’s just 62 degrees and gray for three weeks straight. You’ll see tourists in shorts and flip-flops looking absolutely miserable while locals are still rocking their Patagonia vests and "Seattle black" (which is just various shades of dark charcoal). Then, almost like a light switch, July 4th hits. Usually, that’s the unofficial start of summer. The clouds break, the Rainier view opens up, and suddenly everyone is at Alki Beach acting like they haven't been Vitamin D deficient since October.
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July and August: The Sweet Spot (Mostly)
When people ask about the best summer in seattle weather, they're really looking for that late July window. Here is the raw data:
- Average Highs: Usually mid-70s to low 80s.
- Humidity: Practically zero. It's a "dry heat," which people from the South laugh at until they realize nobody here has air conditioning.
- Daylight: This is the part that trips people up. Because we’re so far north, the sun stays up until 9:00 PM or 10:00 PM.
It’s glorious. You can finish a full day of work, drive to a trailhead in the Cascades, hike for two hours, and still get back before it’s pitch black. But there’s a catch. Recently, the "perfect" weather has been interrupted by what we now call "Smoke Season."
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The New Reality: Heat Domes and Wildfire Smoke
We have to talk about the 2021 Heat Dome. It changed how we think about the PNW. Seattle hit 108°F. For a city where historically only about 44% of homes had AC, that was a disaster. Since then, the summers have felt a bit more unpredictable.
Now, we watch the wind patterns from Eastern Washington and British Columbia. If a wildfire starts and the wind shifts west, the entire city gets choked in a hazy, orange apocalyptic shroud. It sucks. It’s the one thing that can ruin a "perfect" Seattle August. One day you’re paddleboarding on Lake Union, the next you’re taping plastic over your windows because the Air Quality Index (AQI) is worse than a smoky dive bar.
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Surviving the Shift
If you're coming here, pack a light shell. Not for rain, but for the wind off the water. The Puget Sound stays around 50-55 degrees year-round. Even on a hot day, as soon as that sun dips behind the Olympics, the temperature drops 15 degrees in what feels like five minutes.
What to actually do with this info:
- Don't trust June. If you want guaranteed sun, aim for the last two weeks of July or the first two of August.
- Check the AQI. Before you plan a big mountain hike, check AirNow.gov. Don't hike in smoke; it's bad for your lungs and you won't see the view anyway.
- Book A/C hotels. If you're sensitive to heat, specifically ask if your Airbnb has cooling. A lot of "charming" older Seattle homes are basically ovens in August.
- Embrace the "Big Dark" exit. Buy a pair of polarized sunglasses. When the sun finally hits the water after a long winter, the glare off the Sound is blinding.
The summer in seattle weather is arguably the best in the country—when it behaves. It’s a short, frantic window of blue skies and mountain silhouettes that makes you forget why you spent all of February crying into a latte. Just don't expect it to start before July 5th.
Next Steps for Your Trip
Check the current 10-day forecast specifically for Sea-Tac airport (where the official readings happen) versus downtown Seattle. The "urban heat island" effect usually makes the city center 3-5 degrees warmer than the surrounding suburbs. If you're planning on being on the water, download a tide chart app; the breeze is significantly cooler when the tide is coming in.