It's not summer in Western Washington until July 5.
Or at least that's how the legend goes: The post-solstice sun is traditionally tepid, taking its time to well and truly grace us with enough heat to consider it summertime. Like clockwork, the real warmth only arrives after July Fourth, which is usually cloudy — it wouldn't be a Seattle holiday otherwise.
Last month, Mother Nature followed the script flawlessly, with the month being Western Washington’s coldest June since 2012, according to the National Weather Service.
When she turns up the heat this week and beyond (spoiler alert: It will be quite warm and sunny on July Fourth), we'll all have something to long for.
Temperatures across the region will begin to soar July 5, catapulting the mercury up to 15 degrees above early July's average temperature of 74 degrees, said Jeff Michalski, a meteorologist with the weather service in Seattle.
After July Fourth, daytime highs are projected to stay above 80 degrees through the middle of the month. Western Washington is projected to receive below-normal precipitation, too, according to the NWS Climate Prediction Center's six to 10 day weather outlook.
A ridge of high pressure began to build offshore Monday, which will be responsible for producing the incoming heat wave and the warmest weather of the year so far across the region.
While the ridge lingered Tuesday, morning clouds were reluctant to scatter, keeping temperatures leashed to around 70 degrees.
"It'll be the coolest day for the foreseeable future," the weather service said.
As the ridge prepares to migrate east, morning clouds won't stick around as long on Wednesday. Temperatures will make up some ground, stretching well into the 70s.
The Fourth of July will bring plenty of sun (no clouds this year!), tugging temperatures across the Seattle area into the 80s and well above average for early July. The coast will remain a touch cooler, in the 60s, the weather service said.
Daytime humidity will steadily move closer to critical levels this week, increasing fire weather concern, especially around July Fourth, the weather service added.
The ridge will park itself over Western Washington Friday, remaining in place and amplifying over the weekend. Highs on Friday will bubble up a few degrees warmer than Thursday.
The weekend will see the mercury stretch into the upper 80s to mid-90s for the interior.
Saturday and Sunday are expected to be the hottest days in the upcoming week for most, with more than a 60% chance of the central Puget Sound region eclipsing 90 degrees. There's an even higher chance from Olympia south along Interstate 5 and eastward into the Cascade valleys and foothills, the weather service said.
Temperatures will hug close to 60 degrees overnight.
This sun-soaked spell is expected to extend "well beyond Sunday," the weather service said, with "no signs of this pattern breaking down."
As high temperatures make a run at 90 degrees this week, the weather service warns of increasing risk of heat-related illnesses, especially in those sensitive to heat or who don't have access to effective cooling and hydration.
People should also be aware that, despite warmer air temperatures, waterways may remain cold across the region.
Snowmelt keeps the temperatures of most rivers and lakes in the 50s this time of year. Puget Sound's temperature is in the mid-50s, making cold-water shock a real concern for swimmers of all abilities.
And is there any chance of rain in the foreseeable future?
"No," Michalski said.
"Summer is coming, and it's right on schedule."
