Forecast: Warmest day of the year today, ‘slight chance of heat dome’ this summer

April showers bring May flowers. This poem from the 19th Century rings so well in western Washington.

Yet this year, those April showers were fewer than usual. The Seattle-Tacoma International Airport (SEA) finished the month about two-thirds of an inch of rain shy of the average 3.18 inches.

Much of the rest of western Washington was also drier than normal in April. For instance, Everett Paine Field had close to three-quarters of an inch of rain all month, well short of the 2.60-inch average.

Those May flowers will enjoy the warmest day of the year thus far on Thursday, as higher pressure aloft over the Pacific Northwest bumps temperatures well into the 70s across much of western Washington. Some locations south, toward Portland and in the Cascade foothills, could reach 80 degrees. April had four days in the 70s, with the 24th being the warmest at SEA with 72 degrees.

The warmer weather is expected to hang on Friday, providing a fine opportunity to view the tulips in the Skagit Valley, as that festival has been extended through this weekend. High temperatures are forecast to be just a few degrees cooler.

Western Washington weekend weather will bring rain

A change is anticipated for the weekend, though. A Pacific frontal system lurking offshore is expected to swing onshore, bringing some rain inland Friday night. Lingering showers should taper off Saturday, yet it will be much cooler with highs only in the 50s. Sunday is forecast to be the better weekend day with some partial afternoon clearing and high temperatures climbing into the upper 50s and lower 60s.

More sunshine is expected to return next week with high temperatures once again reaching into the 70s. The average high temperature in early May is in the mid-60s.

The spring sunshine and warmer temperatures are usually, always welcome. Yet, the Cascades and much of the Puget Sound region are abnormally drier than average for the year. SEA finished April close to four inches below normal for the year. Olympia has a six-and-a-half-inch deficit, and Everett–Paine Field has had only just over four inches of rain total this year, only 31% of average.

Puget Sound region sees moderate drought conditions

The mountain snowpack also finished the winter season below average. The nation’s Drought Monitor highlights the Cascades and much of the Puget Sound region as currently abnormally dry or moderate drought conditions.

In mid-April, the Washington State Department of Ecology declared a drought emergency in parts of central Washington through the Yakima River valley basin. That declaration released $4.5 million in emergency relief for communities, people, and businesses in that region. The drought declaration also marks the third year in a row, highlighting the ongoing dry conditions.

Chance of another ‘heat dome’

The drier-than-usual conditions do not look to have any substantial relief forthcoming as well. The latest seasonal weather outlook for the rest of this spring and summer offers good odds on warmer-than-average temperatures, while rainfall is expected to be near or just below average during the driest time of the year. This outlook follows the trend witnessed so far this century. The chance of another “heat dome” is quite slim, yet these days, it cannot be ruled out.

The more limited water situation offers some concerns. Water supplies may be more limited, particularly in mountain-fed rivers and streams. This situation is an issue for water consumption, agriculture, hydro power generation, fish, and recreation.

The reduced mountain snowpack and dry conditions mean the wildfire season has a better chance of being longer, starting earlier, and finishing well into this fall. Since 2017, western Washington has suffered from wildfire smoke—resulting in poor air quality six out of the last eight summers.

Recommendations for dealing with dry conditions

What can be done? Prepare to use less water when possible. For example, bathe cars in a car wash as opposed to at home. Consider swapping out the lawn for more drought-resistant yard plants.

With the ongoing dry conditions, avoid outdoor burning and ensure campfires are cold when leaving a campsite. Also, keep all burning materials inside vehicles. Around homes and businesses, create a defensible space. Visit Firewise USA for helpful tips to produce a defensible space and reduce the threat of a wildfire reaching your structure.

The calendar has rolled over into May. More spring-like, warmer weather lies ahead. The sun angle in early May is the same as in mid-August. To avoid sunburn, it is time to lather on that sunscreen and take other sun precautions when outside.

The days continue to get longer. Sunrises are now before 6 a.m., and sunsets will reach 8:30 p.m. on May 7. Safely enjoy the weather as spring marches on toward summer, which starts in just seven weeks.

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