Western WA’s spring sunshine ends this weekend as showers return

For those enjoying this week’s spring sunshine, all good things do come to an end.

Higher pressure aloft that has steered Pacific weather systems elsewhere this week and provided the sunshine is forecast to shift inland on Friday. High temperatures have been warming since the big cool down on Tuesday. Friday will reach a peak, with readings climbing into the mid-60s to mid-70s across the interior of Western Washington. The coast will feel cooler with onshore breezes and highs in the 50s.

A weather system just off northern California and another moving southeast from the Gulf of Alaska will combine to bring a significant change in weather over the weekend. The bulk of the weather is slated to swing onshore into northern California and Oregon, yet clouds and some showers are expected to track into Western Washington. High temperatures will cool to near the average for mid-April, in the mid- to upper 50s.

Rain amounts will be rather light, perhaps a tenth of an inch or so. Mountain snow levels should remain above the passes, dropping from 7,000 feet to at or above 5,500 feet by Sunday.

April showers bring May flowers

The showery unsettled weather is expected to continue off and on through next week. The return of spring showers brings to mind the phrase “April showers bring May flowers.”

The phrase originated in the United Kingdom, where the climate is quite similar to that of the coastal regions of the Pacific Northwest. In 1557, poet Thomas Tusser wrote, “sweet April showers, do spring May flowers.”

More than a century earlier, in The Canterbury Tales, Geoffrey Chaucer wrote, “March winds and April showers bring forth May flowers and June bugs.” History shows this is where the “April showers bring May flowers” phrase began.

Peak rainbow season

The return of unsettled weather and showers this weekend is a reminder that spring is the peak rainbow season. Rainbows can occur any time of year, but the combination of spring showers and a higher sun angle than in winter creates a greater number of rainbows during spring.

Rainbows are created by sunlight and rain from clouds or water droplets hanging in the air after a rainfall. Sunlight enters a water droplet, slowing and bending as it passes from air to denser water. The light reflects off the inside of each rain droplet, breaking it into its different colors. When the light then exits the rain droplets, it creates a rainbow.

Sunlight is composed of a spectrum of colors – many wavelengths of light. Violet is the shortest wavelength and bends the most. Red has the longest wavelength and bends the least. When you see a rainbow, the light reflecting back to you with the sun at your back will show all the colors between violet and red, with violet at the bottom and red at the top.

Spring is here, and it’s rainbow season — among the most beautiful displays of nature. If you see one, take pictures and share them on the KIRO FM Facebook site so everyone can enjoy them.

Ted Buehner is the KIRO Newsradio meteorologist. Follow him on X and Bluesky. Read more of his stories here.