Tuesday is Seattle’s last 60+ degree day in March

The sunshine and unseasonably warm temperatures will continue through Tuesday as the spring equinox arrives shortly after 8 p.m. Then, cooler moist spring weather will arrive starting Wednesday and continue into the coming weekend.

The final weekend of winter certainly had plenty of warm spring-like sunshine. High pressure aloft and low-level flow moving from inland areas to the ocean generated clear skies and record daily high temperatures. On Saturday, Forks climbed to 80 degrees before cooler ocean breezes arrived on Sunday.

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In the western interior, record highs melted away. At Seattle-Tacoma International Airport, Saturday’s high of 74 snapped the old record of 72 set in 1947. On Sunday, the high of 71 degrees tied the previous record also set in 1947.

Olympia reached 74 degrees both on Saturday and Sunday, breaking the old records of 70 degrees on both days set in 1972 and 1978 respectively. Bellingham’s highs of 68 on Saturday crushed the old record of 63 established in 2010, and Sunday’s high of 67 knocked off the previous record of 63 set just a few years ago in 2019.

The warm high-pressure system over the region is forecast to begin to break down through Tuesday. Monday and Tuesday’s highs will still be well above the average highs in the mid-50s, warming well into the 60s with lows only in the 40s.

By the first full day of spring on Wednesday though, scattered showers and much cooler more seasonable temperatures will return. The first in a series of relatively weak Pacific weather systems will move ashore, producing scattered showers and dropping high temperatures back down into the 50s.

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More weather systems will maintain on-again, off-again showers the rest of the week and into the coming weekend. For allergy sufferers, the cooler wetter weather will be welcome since many tree species generate a surge of pollen in the air during the early season warm spell.

In the mountains, freezing levels over the weekend were above 10,000 feet. By Wednesday, snow levels are expected to drop to around 4,000 feet, and gradually fall to nearly 2,500 feet by the weekend, bringing much-needed snowfall back to the passes. Motorists crossing the Cascade passes should be prepared for a return of more winter-like conditions on the roadways.

The late winter warm sunshine over the weekend and early this week was welcomed by many. Temperatures were the warmest experienced since mid-October last year. Yet, all good things do come to an end as this week’s weather returns to more “normal” March spring weather.

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.