Monday warmest day of week, followed by autumn-like weather

Can it be? This week is the final full week of the summer season. The autumn equinox arrives early on Sunday, Sept. 22, at 5:43 a.m.

Yet this week’s weather is going to feel like fall has already arrived, similar to last week’s conditions. Monday should be the warmest day of this week, with sunny skies after areas of morning fog. Highs will range from the mid-60s to mid-70s.

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But another offshore Pacific frontal system is set to spread clouds inland Monday night with rain developing Tuesday. High temperatures will be cooler, only ranging from 55 to 65, about five to 10 degrees below this week’s average temperatures.

The cloud cover will likely hide this month’s full moon Monday night – the Harvest Moon. Yet, it is possible the moon may play peek-a-boo through the clouds.

In the wake of the Pacific frontal system, Wednesday should have a decreasing chance of showers with some sun breaks. The Seattle Sounders game Wednesday evening against San Jose at Lumen Field will be dry, with game time temperatures only in the lower 60s.

For the Seattle Mariners’ home series against the New York Yankees, the stadium roof is expected to be closed for Game 1 Tuesday evening, but open for the ensuing games Wednesday and Thursday.

More from Ted Buehner: PNW temperatures drop this week as region prepares for autumn

Higher pressure aloft is expected to build Thursday and Friday, resulting in some sunshine and drier conditions. High temperatures will be mainly in the 60s for the rest of the week. Lows throughout the week will feel autumn-like, in the mid-40s to 50s.

Heading into the weekend, the drier weather is expected to hold as the fall equinox arrives Sunday morning, a nice way to kick off the first day of fall.

Ted Buehner is the KIRO Newsradio meteorologist. You can read more of Ted’s stories here and follow him on X, formerly known as Twitter.