Marine clouds spread over much of western Washington on Monday morning after rising low-level onshore flow from the Pacific Ocean pushed in overnight, leaving the region gray again just as many people were asking what happened to the weekend sunshine. A brief few sunbreaks were possible late Monday, but the opening looked fleeting.
Temperatures were expected to stay well below the weekend level, with Monday highs running about 10 degrees cooler and struggling to climb above 60 degrees. Tuesday was forecast to bring more persistent marine clouds and highs near 60, with only a slim chance of a late-day isolated shower through then. There was no rain in sight in the latest forecast discussion, and longer-range charts did not show a threat of rain well into next week.
The turn came midweek. By Wednesday, higher pressure aloft was expected to build over the region as the low-level onshore flow tapered off, allowing the sun to return and highs to climb into the 60s. Thursday was shaping up to be the brightest day of the stretch, with plenty of sunshine and warmer temperatures, and afternoon highs were forecast in the mid-60s to mid-70s across western Washington. Marine clouds were expected to make a brief return Friday morning before giving way to afternoon sunshine.
That warming trend could push some areas back toward the year’s first real heat milestone. At Seattle-Tacoma International Airport, the warmest temperature so far in 2026 has been 74 degrees, recorded on April 19, and highs on Thursday or Sunday could top that mark. By Sunday, temperatures were expected to reach the 70s in many western Washington locations, while mountain freezing levels were projected to rise from around 6,000 feet through Tuesday to 8,000 feet or higher for the rest of the week and into the weekend.
The bigger picture is simple: after a few days of spring showers and below-average highs, April looks set to finish dry, and the dry spell is expected to last into at least the first week of May. That matters because the average first day of 80 degrees or better at SEA is May 20, and nearly all record highs there reach 80 degrees or better through the first half of May. In other words, the region is moving quickly from a cool, damp stretch into a warmer run that could set up an early taste of summer weather.
