Seattle Weather warms toward 77-degree Sea-Tac Sunday
Seattle weather is set for a warm stretch this weekend, with temperatures expected to climb into the 70s to low 80s on Sunday and Monday. Sea-Tac could challenge its 77-degree Sunday record high if the airport reaches 80 degrees, which would be its first 80 since September.
Sea-Tac and the south Sound
Saturday is expected to start with patchy morning clouds before clearing to mostly sunny skies, and highs should reach the mid-60s to mid-70s. The warmest readings are likely in the south Sound, where the air mass is expected to peak as a strengthening ridge of high pressure over western Washington and British Columbia combines with developing thermal low pressure west of the Cascades.
That setup is expected to promote offshore winds and push temperatures well above normal for early May. Sea-Tac’s Monday record high is 85 degrees, though that mark appears less likely to be broken than the Sunday record.
Boating season and cold water
The Pacific Northwest’s opening day of boating season is Saturday, but water temperatures will remain in the 40s and 50s. Those readings fall within the range of risk for dangerous cold-water shock, even as air temperatures rise across western Washington.
Conditions are expected to remain dry into next week before temperatures cool slightly into the mid-60s to low 70s as onshore flow returns. Seattle averages historically just under two inches of rain in May, and the city also gains 60 to 70 minutes of added daylight over the month, with sunsets stretching by about 20 minutes every two weeks.
