Heatwave in Seattle – A Start of a Vicious Cycle?

7 Sep 2021 7:35 PM | Lea-Ann Berst (Administrator)

by Hyon K. Rah – Chair, Environment & Sustainable Development Committee

September 2021

When I tell people about my work in sustainability and climate resilience planning in the built environment, I am often asked this question: “Where would you go to stay safe from the impacts of climate change?” While there is no certain safe place from the disruptions of climate change—hence the importance of and responsibility for prevention and mitigation—some regions are expected to feel the impacts less than others. One of the first places I would have mentioned is my hometown of Seattle. Although there are other risks there—including the “Big One,” a magnitude 9 earthquake that’s said to be coming any time—the Pacific Northwest was expected to fare better than other regions.

This, of course, was before the crazy heatwave in late June of this year. Instead of the relatively cool weather that’s characteristic of June in Seattle (locally known as “June gloom”), the temperature reached three digits and stayed there for three days, peaking at a record-breaking 108 degrees on June 28th. In the evenings, temperatures only cooled into the 70s. To put into context how unusual this is, there were only three days above 100 degrees in Seattle in the last century before the heat wave in June. Seattle’s average daytime high in June is in the upper 60s to lower 70s, and it drops to the mid to low 50s in the evenings. Typically, the mild temperatures and low humidity levels in the summer in Seattle meant natural ventilation was enough to cool most buildings. During the heat wave, however, most people were left to power through the 100+ degree heat without air conditioning. The heat wave was linked to hundreds of deaths across the Pacific Northwest.

My family and friends in the area told me it would pass and things would return to normal soon. Sadly, less than two months of normalcy was all they were afforded. The temperature gauge hit the upper 90s again in mid-August, about 20 degrees higher than the monthly average. The word “abnormal” was starting to seem inappropriate to describe the extreme heat in Seattle. I started to hear friends and family who never had air conditioning say they were considering installing it in their homes. I completely understand where they are coming from, having experienced a rather swift shift in attitude towards air conditioning myself after my first summer on the east coast. That said, I also find this development worrisome.


You might remember the state-wide power outage in Texas back in February. It was caused by surging demand for mechanical heating to cope with the unusual cold spell. In a similar way, thousands of residents in the Seattle area experienced outages due to the increased electricity demand for cooling during the heat wave. The outages in Seattle were nowhere near as large as those in Texas, possibly because most homes in the Seattle area are not equipped with mechanical cooling units to turn on and overwhelm the supply of electricity. Afterall, Seattle is the least air-conditioned city in the country. According to 2019 figures, only 44.3% of homes had air conditioning compared to the national average of 89%. Things have been quickly changing, however. In 2013, less than one-third (31%) of homes in Seattle had air conditioning; that’s an increase of over 13% in just six years (Figure 1). I expect the increase in air conditioning to continue, and, with that, the demand for electricity and the risk of larger-scale outages during the times when people need cooling the most.

Even if the additional power supply is made available, I remain worried because of how the additional energy might be produced. Will there be enough renewable energy sources to meet the increased demand for air conditioning? One of the major sources for Washington State’s renewable energy production, hydroelectric power, has been in decline, and it has been challenging enough to try to close that gap with other renewable energy sources such as solar and wind.

Figure 2: Change in average global temperature relative to 1850-1900, showing observed and simulated temperatures


The past five years have been the hottest on record since 1850, according to the new IPCC report on climate change which came out in August, 2021. The IPCC, or Intergovernmental Panel on Climate Change, is a United Nations body charged with providing objective science-based information related to climate change. The report noted there was a 1.96°F (1.09°C) increase in the earth’s surface temperature observed over the last decade and presented concrete evidence that human factors have warmed the climate (Figure 2).

I mention the human influence on the climate not to point fingers but to highlight the fact there are clearly things we as a society can do to mitigate problems we had a hand in creating. In the case of dealing with more frequent heat waves in Seattle, for example, doing our part could entail ensuring air conditioning units are as energy efficient as possible and that the additional energy needed is generated using renewable sources.


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