The Perfect Storm that Led to Portland’s Heat Wave

The sun hovers over Portland’s skyline. On three cloudless Portland summer days, temperatures within the city reached as high as 124 degrees in some areas, smashing records for the region. Illustration by Pearl McNames.

The air was not just around us, it was on us. It suffocated us and had a mind of its own. It was uncontrollable heat, inescapable outdoors, too much to handle. For those outside, the heat was the enemy. For some inside, trapped in sweltering homes without air conditioning, it was an encroaching threat. It was something entirely unheard of in the city of Portland, a show of power by an oppressive sun. It was by far the worst heat wave the Northwest Coast region had ever recorded.

At one point on Monday, June 28, 2021, the air temperature measured at the Portland International Airport by the National Weather Service (NWS) was 116 degrees Fahrenheit. This broke the all-time record for temperature recorded in the city by four degrees. That previous record was set on June 27, 2021. The temperature on the 27th also broke the all-time record by four degrees, breaking a mark that had been set on June 26, 2021. One of the gloomiest cities in America, one shrouded by at least 75 percent cloud cover for 222 days per year, the second-most in the country, was hotter than the Mojave Desert, according to OPB. That heat led to the deaths of at least 62 people in the city of Portland alone, according to the New Yorker, and estimates from the Washington Post put the death toll much higher than that. In some regions like the Southwest, heat like that experienced at the end of June, while intolerable, would not be entirely out of the ordinary for the summer. In the Pacific Northwest, it was a catastrophe.

When Tyler Kranz, a meteorologist at the NWS’s Portland division, and the meteorology team looked at the long-term forecast—4-7 days in advance—in mid-June, they saw a forecast that was unusual for Portland as a whole, and just about unheard of in June: a range of temperatures from the high-90s to 117 degrees in the future. At the time of year in question, the typical temperature in Portland is under 80 degrees, according to the NWS, so even the low end of that forecast would be unusually high, and the high end showed unprecedented heat for the temperate rainforest west of the Cascade Mountains.

After the forecast showed such extreme temperatures, the NWS helped work with the public to prepare for the potential disaster. cooling centers were set up, largely inside libraries, as air-conditioned areas in which residents could avoid the deadly heat. These actions were strengthened by heavy messaging from the NWS, 211 services, and others, so people would learn about previously-unknown resources in time for the heat wave. The NWS also worked with Emergency Managers, says Kranz, who are appointed in each county, and with “hundreds, if not thousands, of partners” to bolster their heat wave aid efforts.

211info, an organization that works with social services to help the community, helped by “[populating their] shared resource database with information statewide about cooling center sites, splash pads, health and wellness information, and potable water,” according to 211info Director of Partnerships Cara Kangas, while also working with TriMet to provide free bus rides to anyone needing access to a cooling center. They worked with the NWS, Emergency Managers, and others to prepare for the crisis.

Over the days leading up to and including the heat wave, a “trough of low pressure” built up in the area, says Kranz, and this effect prevented the hot air from escaping. As the hot air compressed and compressed, it eventually reached a point at which the hot air was sinking at a large scale, the reverse direction of thermals, or currents of rising warm air, in most systems. This is called the heat dome effect, and it’s what allowed the Northwest to build up in temperature more and more until it reached its record highs.

Temperatures vary throughout cities. Depending on nearby tree cover, the amount of pavement in the area, the level of the building someone is in (because warm air moves upward, higher floors of buildings are much hotter), and other factors, the temperature may be significantly warmer or cooler than in other areas. Places with outlying temperatures are known as “urban heat islands.” Due to the cooling effect of the vast Forest Park in West Portland, for example, heat islands are extremely pronounced in the city, and when heat levels rise to those of the heat dome this summer, they can lead to death.

One cause of variation in heat throughout cities is redlining, a process in which early 20th-century housing policy kept people of color from living in predominantly-white neighborhoods, leading to widespread segregation. These policies led to some neighborhoods, which were majority-BIPOC and lower-income areas, getting fewer resources than they should have. In addition to underfunding, the lack of influence for such neighborhoods prevented residents from resisting urban expansion like the construction of new highways. These helped lead to the “heat island” effect: Portland’s redlined areas tend to be far hotter than other areas of the city. In a ZIP code for SE Portland’s Richmond neighborhood, four people died during the heat wave, according to Willamette Week, showing the effects of these actions. While the era of redlining is long over, many formerly-redlined neighborhoods in America still receive fewer resources than their once highly-rated counterparts. A study by New York University found that, within the 500 largest American cities, life expectancy varied by as many as 20 to 30 years depending on the neighborhood in which an individual presided.

The difference in neighborhood temperature throughout Portland is greater than that of most major cities in the United States: It is regularly 12 degrees hotter in the redlined neighborhoods than in those that were rated highest by redliners, according to a study by Portland State University led by Dr. Vivek Shandas. As a result, some parts of the city were unbearable beyond words, like one corner in Lents that registered at a blistering 124 degrees when Shandas measured it that day, where the sidewalk reached 180 degrees, according to Willamette Week. A sidewalk that hot could give someone third-degree burns.

Because of these discrepancies, measuring heat in the city is not so simple. The NWS collects its measurements largely from a group of automated weather stations at local airports, according to Kranz. There are other stations that residents of the city have at places like their homes through the Citizen Weather Observer Program, he says, but they are less reliable and less useful than the measurements obtained at the airports. “Typically they are just measuring the temperature,” Kranz says, and “we’re not quality-controlling that data,” so they do “take [the data] with a grain of salt.” With the only reliable estimates coming from the airport, the NWS can only provide a simple description of the weather for a city where the temperature could be far higher or far lower in certain areas.

The NWS measurements also fail to encompass every condition because they measure under the shade, which lowers the heat estimates, according to Kranz. The WetBulb Globe Temperature attempts to quantify the stress of the heat under terrible conditions, like while someone is in a humid environment, at noon (when the sun is at an angle that leads to greater heat), with low cloud cover and calm winds, the perfect formula for conditions hot enough to cause extreme stress. During the June heat wave, the WetBulb temperature registered as Extreme, the highest level of the scale.

The WetBulb severe effects were compounded by a lack of regional preparedness. Because of the Pacific Northwest’s typically-mild climate, many residents have long declined to buy air conditioning units, instead relying on fans and cold water to keep them cool during the area’s tolerable summer days. Per the New Yorker, 21 percent of homes in the city lack air conditioning. One Franklin student recalls returning to his home on the second of the three days of the June heat wave after having worked as a lifeguard for several hours. When he entered his then-boiling home, he says he thought to himself, “I’ve got to get somewhere. This is not okay.” Even his basement was 80 degrees, he says. He and his family escaped to a friend’s air-conditioned home. Others were not so lucky: many elderly people were stuck in homes without A/C, and one was carried out of their Richmond neighborhood house in a body bag, according to the New Yorker.

Lifeguards often work at outdoor pools in hot conditions, since the summer is when swimming pools are most popular, and their shifts can be spent under the sun during the hottest parts of the hottest days of the year. During the heat wave, this caused problems for some lifeguards in Portland.

Many of the branches had enough staff to handle the heat waves, but working 20-60 minutes straight within the lifeguard rotation, usually 40, would be tiring and unsafe, so extra precautions were taken. “It was mandated that we jump into the pool between every rotation,” says one lifeguard, which helped them stay wet and cool. They were given cold water, ice buckets, and bandanas, which could help them cover their heads with something cold at all times. They “tested” lifeguards on their ability to pay attention by having off-duty guards jump into the pool, giving the ones still working another chance to jump in. These were in addition to typical precautions like the use of sunscreen, hats, and other materials that help keep guards cool on a daily basis. One pool saw a shortage of lifeguards over the summer, and understaffed pools mean longer shifts under the heat of the sun. According to multiple lifeguard sources, the heat led multiple lifeguards at that pool to suffer heat-related illnesses, though this has not been confirmed by Portland Parks and Recreation.

Unfortunately, extreme weather events like these may happen again in the near future. Due to the excessive use of fossil fuels and the emission of greenhouse gases, the world continues to heat up, and that climate change increases the risk of devastating weather. A study by World Weather Attribution (WWA) concluded that the June heat wave, which would occur 1 in 1000 times in today’s climate, would be “virtually impossible without climate change.” If emissions continue to rise at their current rate, WWA projects that, by the 2040s, such events will begin to happen once every five to ten years. The continued use of fossil fuels is exacerbating the issue, making severe events far more likely to happen. 

At the end of the terrible third day, the one in which temperatures were at their highest, our world started to cool and return to normal. One student remembers walking outside in that weather and feeling somewhat cold. “I [wondered] how hot it is, or how cold it is,” he says. “And it said 80 degrees. And I was like, ‘What? It’s 80 degrees cold.’”

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