The National Center of Environmental Information (NCEI), formerly known as the National Climatic Data Center (NCDC), recently released the 2022 Washington State Climate Summary. The summary offers a sobering list of key highlights that many people have sensed through their experience during the past few decades.
- “Temperatures in Washington State have risen almost 2 degrees Fahrenheit since the beginning of the 20th century. Winter warming has been evident in the below average number of freezing days and very cold nights since 1990. Under a higher emissions pathway, historically unprecedented warming is projected to continue through this century.”
- “Rising temperatures will lead to earlier melting of the snowpack, which plays a critical role in spring and summer water supplies. The combination of this earlier melting and more precipitation falling as rain instead of snow may lead to an increase of springtime flooding” (east slopes of the Cascades).
- “Wildfires during the dry summer months are a particular concern for Washington, and the frequency and severity of wildfires are projected to increase.”
- “Overall, warming will lead to increases in heat wave intensities but decreases in cold wave intensities. Unlike other locations in the United States, Seattle and other urban areas are rarely exposed to very high temperatures. Future heat waves, particularly an increase in the frequency of warm nights, could stress these communities, which are not well adapted to such events.”
On that last point, local authorities point out that many Pacific Northwest homes including those in the North Sound are designed to let in and retain heat with south facing windows, insulation, and more. For homes without air conditioning, indoor temperatures do not typically peak until the outdoor temperature is cooler than indoors, and the hotter the event, the later this crossover occurs.
The late June 2021 heat wave was a great example of this indoor/outdoor temperature exchange. With nighttime temperatures only dipping into the 60s and lower 70s during the heat wave, the coolest it ever got in a home with the windows all open was around daybreak. Warm morning low temperatures made this historic heat wave critically important when it came to human health and relief from the heat.
Research oceanographer Ruping Guan analyzed world temperature data from 1952 to 2011, and the bottom line was summer is longer and all other seasons are shorter. Specifically, the length of summer increased from 78 to 95 days or 4.2 days per decade (worldwide). The length of winter, spring and autumn all shrank, winter down 3 days, spring 9 days and fall down 5 days. The next decade during the 2010’s was the warmest on record worldwide, continuing this seasonal trend.
The National Weather Service’s Climate Prediction Center just released their latest seasonal weather outlook for the rest of the spring through the coming winter. For May and June, the trend is for warmer than the cool April experienced thus far with around average precipitation. But for this summer – July through September, the wager has been raised on a warmer than average summer, continuing a trend for much of this century thus far. Summer precipitation showed no significant trend, though it is the driest time of the year.
The odds on another historic late June 2021 heat dome are quite slim, but given circumstances around the globe, it cannot be ruled out. And if you have not been aware, India has been suffering an extended heat wave with temperatures well above 100 degrees F with humidity for about a month.
Temperatures during this month of April may be cooler than average, but as summer arrives, those cool temperatures can turn around quickly. It is best to prepare now for the next heat wave.