Blue moon coming to Puget Sound region, but will we be able to see it?

The next blue moon is set to rise Wednesday evening in the Puget Sound region’s eastern sky at 8:13 p.m. The question is, will you be able to see it?

A weak upper-level low-pressure system is set to move ashore Tuesday, followed by a similar weather system Wednesday night and Thursday. These systems will not only bring clouds and fresher, cooler Pacific air to help mix out this weekend’s lingering wildfire smoke but also bring a rising threat of showers and even the possibility of a thunderstorm.

At this point, when the blue moon rises Wednesday evening, that will likely be the best opportunity for breaks in the cloud cover, permitting what may be a “peek-a-boo” moon. Cloud cover is expected to thicken overnight Wednesday as the following weather system moves onshore.

This blue moon is also a supermoon. In fact, this supermoon will be the closest to Earth of the year, meaning it will be the biggest and brightest this year. The moon’s orbit around Earth is an ellipse versus a full circle, meaning there are times when the moon’s orbit gets closer to the planet.

There are two definitions of a blue moon. One is that when a second full moon occurs in the same calendar month, and that is the case with the sturgeon full moon early this month. The other blue moon definition is that four full moons occur in a season, such as the summer season.

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Going back in history, the term blue moon originated following the 1883 eruption of Krakatoa, putting so much volcanic dust in the atmosphere that the moon appeared blue in color.

The phrase once in a blue moon refers to a rare event. But, in fact, astronomical blue moons occur more frequently, occurring on average about every 33 months, according to space experts. The last blue moon was in August 2021 and was the fourth full moon that summer.

The incoming weather systems may bring the string of 70-degree or greater high-temperature days at Seattle-Tacoma International Airport to an end as well. The warm temperatures over the weekend brought the sequence of 70s or better to 68 days. Forecast high temperatures at times this week are expected to rise only into the upper 60s.

Higher pressure is forecast to rebuild over the Pacific Northwest in time for Labor Day weekend, with temperatures rebounding back into the 70s and lower 80s across Western Washington with sunshine.

On Wednesday evening, during the largest and brightest supermoon of the year, the question will be if we are singing the blues if the blue moon hides behind clouds.

Follow Ted Buehner, the KIRO Newsradio meteorologist, on Twitter.