Rain, cooler temps and possible mountain snow on tap for WA this week

The early fall weather has had plenty of sunshine and mild temperatures. Yet you knew that wasn’t going to last forever. This week’s weather will be a stark contrast with rainfall and much cooler temperatures.

This past weekend’s weather likely may be the last sunny weekend with pleasant sunshine until next spring. It was perfect for exploring pumpkin patches and viewing the fine, colorful fall foliage this state has to offer. Weekend temperatures warmed into the 60s to mid-70s across Western Washington.

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Starting Monday, the first of a series of Pacific weather systems is due to sweep onshore with rain and temperatures around 10 degrees cooler than the weekend. This first system is not expected to have too much punch, providing just a tenth to a quarter-inch of rain along the Interstate 5 (I-5) corridor and the western interior, and close to a half-inch along the coast.

The next weather system, due to arrive Wednesday, will bring a greater amount of rain and some blustery winds that will likely blow down many leaves. A much cooler air mass moving southeast from the Gulf of Alaska is anticipated to follow this weather system for showery weather and the possibility of a thunderstorm into Thursday.

This cooler air mass is also expected to drop snow levels close to 4,000 feet Thursday. Paradise on Mount Rainier and higher mountain pass highways will likely see some accumulation and even Stevens Pass may turn white for the first time this fall.

Thursday will also involve the Hunter’s Full Moon, potentially visible during breaks in the nighttime clouds.

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The showers are expected to taper off Friday for a break in the wetter weather, in time for Friday night high school football games and the Seattle Reign taking on the visiting Houston Dash. High temperatures during the latter part of the work week will be cool – only in the 50s with lows in the 40s.

The outlook for the coming weekend has the potential for more wet weather, not the best weather as the Portland Timbers visit the Seattle Sounders on the pitch Saturday night.

The pleasant, generally dry fall weather was due to end. At least we got to enjoy it while it lasted.

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