Fire Weather Watch issued here as Seattle bakes in the 90s

SEATTLE -- For the third time this year, much of Western Washington reached the 90 degree mark, with Seattle warming to 94 degrees Thursday and another hot day on tap Friday.

But it's what's coming to end the heat wave that has forecasters concerned: the potential for lightning-created wildfires, even in the greater Seattle area.

The National Weather Service has issued a rare Fire Weather Watch for almost the entire Western Washington lowland areas, save for the ocean beaches and far southwestern Washington. The Watch means our tinder-dry conditions are right for wildfires to be started.

The concern stems from the potential for thunderstorms to move through our region Saturday afternoon through Sunday morning.

But in the short term, very hot weather remains the focus. A thermal trough remains entrenched across the region, clearing out the clouds and boosting temperatures into the 90s for many locations.

In addition to Seattle's 94 Thursday, it was also 94 in Tacoma, 95 in Olympia, 91 in Bremerton, 93 in Renton, 92 in North Bend, and 97 in Shelton.

Further north, it was a little cooler, emphasis on "little": Port Angeles hit 88, Everett and Friday Harbor hit 87, while Bellingham, and Mount Vernon each checked in at 85. Arlington did manage to join its southern friends in reaching 90.

Over on the coast, it was a mixed bag of weather as the cool marine layer made its trek north. Astoria never got out of the clouds and managed a cool 66 degree high. Hoquiam rapidly warmed to 83 in the late morning, but then dropped 12 degrees in an hour from 81 to 69, eventually bottoming out at 61.

But Forks had no such cooling and reached 89 Thursday.

The heat has prompted an Excessive Heat Warning to be issued for the greater Puget Sound area, the Cascade foothills and Southwestern Washington through Friday night.

By Friday, the coast should remain cool into the 60s and 70s as the thermal trough moves inland and the marine breezes return, but no such luck for the interior locations. For Seattle, we're going with another 94 degree high. Southwestern Washington and the Cascade foothills could nudge into the mid-upper 90s.

The thermal trough moves into Eastern Washington Friday night which will kill off the dry, east wind and the 90s for Saturday, but it'll still be warm (in the low-mid 80s) and we'll introduce some humidity as well as the upper air flow turns from the south.

The humidity is the harbinger of the storms to come later Saturday into Sunday as an area of low pressure moves through the area from the south, destabilizing the atmosphere and adding moisture and lift to the tremendous amount of heat energy already in place. It's a recipe for towering thunderstorms with frequent lightning and therein lies the concern since any spark from lightning could touch off a wildfire.

Thunderstorms will taper off from south to north as we get through the day Sunday and temperatures will cool back to more the more typical 70s.

You are right, it's usually not in the 90s this often

Thursday and Friday will mark the third and fourth day above 90 in Seattle. Seattle averages between 2-3 days a year above 90 with a day over 95 about every other year, last occurring in 2010. But 90s have been way more frequent of late. In 2009, we had seven days in the 90s, and six days in 2010. We took a 90s break in 2011, only reaching 87 that year, but have already reached 93 twice earlier this month.

So getting four days in the 90s in a summer is not unheard of, but bunching them together in August is rare. According to Jason Phelps, getting four days at or above 90 in August has only happened three times before -- six in 1977, five in 1981 and four in 1967.

(Of course, it could be worse. Our sister station in Bakersfield, California has this story about a garbage can that spontaneously exploded in a garage there this summer. Triple digits are common there in the summer but they've been pushing 110 degrees of late.)

The requisite "I'm too hot, I need some news to make me feel cooler" segment

If you're melting along with no air conditioning and your home can now double as a pizza oven, here is some news to help at least perhaps make you think about cooler air.

First of all, the new 30 day forecast is out for September and while it looks like it'll remain dry across Western Washington, forecasters believe the hot ridge of high pressure will return to the Midwest and East Coast, leaving the West Coast cooler than normal -- very similar to the June and July we went through this year.

And if you can't wait until September, this nearly 6 minute video of gentle, Seattle rains might help.

As for the real cooler air, it'll start its return on Sunday when we'll be gradually getting back to "Seattle normal" with morning clouds, then sunshine with decreasing humidity and highs back into the 70s.