Seattle has ‘air-conditioned weather’ compared to rest of US
Jul 19, 2023, 11:59 AM | Updated: Aug 14, 2023, 2:15 pm
(Photo by George Rose/Getty Images)
Phoenix has had 19 days of 110-degree high temperatures in a row and counting. Miami has had over a month of 100-degree heat index (temperature and humidity). The shallow waters surrounding the Florida peninsula have surged into the 90s – bath water.
The planet’s warmer air mass can hold more moisture and has resulted in numerous heavy rainfall and flash flood events, most recently in Vermont and Pennsylvania. In addition, Canadian wildfire smoke has surged into the lower 48 several times already this summer from Montana to New England and as far south as Washington D.C. and Atlanta.
More Seattle weather updates: Seattle’s sunny weather might be too much of a good thing
These fingerprints of our warming planet are being felt around the world. Just in the past week, South Korea and Japan have suffered flash flood events, India and many parts of Europe have already suffered several excessive heat waves (including this week), and on Monday there was a report from Northwest China of 126 degrees – matching Death Valley readings.
Meanwhile, the Seattle-area is enjoying what could be called, air-conditioned weather. When Major League Baseball All-Stars were in town a week ago, many expressed how great the weather was, even expressing it felt like air-conditioned weather compared to where they came from.
Why is our region not suffering the excessive weather other parts of the nation and the world are experiencing? Fortunately, onshore airflow from the Pacific Ocean frequently moderates temperatures, keeping the Seattle-area from feeling what many other parts of the country and the world are feeling.
Every once in a while, though, that moderating onshore flow from the Pacific switches to offshore flow — from the interior of the Pacific Northwest toward the coast. That is when temperatures can soar well above average.
For instance, last summer, Seattle-Tacoma International Airport had a new record of 13 days of 90 degrees or higher thanks to periods of much warm offshore flow, knocking off the previous record of 12 days in 2015. So far this year, there have been only two days of 90 degrees or better at Sea-Tac.
The greatest example of a major heat wave in the region was during the tail end of June 2021. A ‘heat dome’ – a strong area of high pressure aloft – parked over the region and produced a period of descending air from above along with the offshore flow, resulting in warming temperatures each day until the weather pattern shifted, permitting cooler air to arrive from the Pacific. Temperatures surged well past 100 degrees, crushing previous all-time record high temperatures across much of the Pacific Northwest.
The latest outlook for the rest of this summer continues to tip the odds toward warmer and drier conditions through September.
More on wildfire season: Washington wildfire season just warming up with high rain deficits
This fine summer weather, though, is raising some concerns. The mountain snowpack has essentially melted away earlier than usual. There has not been any meaningful rainfall since June 20, about a month ago. Looking at longer-range weather forecast charts, there is no ‘real’ rain in sight through the end of this month.
Conditions are dry, and weather and wildfire authorities are keeping an eye on how everything goes. Nothing can be done about the warm, dry conditions, yet the third element of the wildfire recipe — fire starts — is something everyone can do to help avoid wildfires. Four out of five fires are human-caused.
Compared to most of the rest of the country, the greater Seattle region is enjoying fine summer weather. Enjoy it and help avoid fire starts until the fall rains arrive.
Follow Ted Buehner, the KIRO FM news meteorologist on Twitter