Adapting to Extreme Heat: Can Cities Prepare for a Hotter Future?

For three weeks beginning in late June through mid-July in 2021, communities across Washington State baked under relentless, abnormal heat, which resulted in the deaths of 100 people. Known colloquially as the 2021 Pacific Northwest heat dome, it stretched across northern California and up into Oregon, Idaho, Washington, western Nevada, and British Columbia. The heat contributed to increased wildfires, damaged roads and other infrastructure, led to crop failures, stressed ecosystems, and strained the healthcare system through a significant increase in emergency department visits and unplanned hospitalizations.

Though 2023 was the warmest year since global records began in 1850, 2024 may be even worse: The National Weather Service (NWS) is predicting a 50-60% chance that temperatures in Central and Eastern Washington will be above normal for the months of July to September, with a 40-50% chance of above-average temperatures in the western part of the state.

As climate change remakes our expectation of what a “normal summer” looks like, some cities are taking steps to plan for extreme heat events, offering guides that other local governments can use as a starting point.

The Vulnerability of Cities

Cities are particularly ill-suited to combat extreme heat events thanks to the urban heat island effect. Heat is absorbed into a city’s infrastructure (i.e., pavement, cement, brick, stone), which raises the overall daytime temperature by 1–7°F higher compared to nearby natural regions. That same infrastructure then re-emits this absorbed heat into the air at night, resulting in evening temperatures that are 2–5°F higher.

Heat islands are also unevenly distributed across cities, with the harshest impacts falling more heavily on low-income communities. For example, analysis found that Tacoma neighborhoods “burdened with the worst extreme heat...also suffer from the worst economic and health inequality.” A similar analysis of Seattle neighborhoods found “a strong correlation between household income and urban heat islands.” Thus, any plan for extreme heat should also include an equity component for households most likely to be impacted.

Heat Action Planning

A major challenge in tackling heat (or any demanding but nebulous issue) is developing a unified response. Several local governments have developed heat action plans that both aim to reduce the heat island effect and spell out heat wave emergency response plans.

Miami-Dade County, Florida

In 2021, Miami-Dade County, in partnership with and funding support from the Adrienne Arsht-Rockefeller Foundation Resilience Center (Arsht-Rock), hired the nation’s first-ever chief heat officer to lead county efforts. In the following year the county, working in partnership with a climate and heat health task force and using input from hundreds of residents, developed an Extreme Heat Action Plan.

This plan covers three broad goals: to inform, prepare and protect people; to cool homes and emergency facilities; and to lower neighborhood temperatures. Then, it outlines 19 actions, such as:

• Creating a network of resilience hubs.
• Increasing shade at bus stops.
• Retrofitting public housing with efficient air conditioning to reduce energy costs.
• Developing workplace protections for outdoor workers, such as requiring the provision of water, shade, and regular breaks.
• Installing diverse types of cool pavements in “low-impact areas” like walkways, bike paths, parking lots and low-volume roads.
• Developing targeted engagement and outreach for residents based on known risk levels.

Phoenix, Arizona

Guided by the Office of Heat Response and Mitigation (created in 2021), Phoenix’s 2024 Heat Response Plan outlines nine broad strategies, including providing publicly accessible indoor and outdoor cooling spaces (e.g., daytime and overnight cooling centers, shaded public areas), supporting cool and safe home environments (e.g., requiring rental units have cooling units, emergency utility assistance fund), and more cross- departmental collaboration of heat-response planning and execution (e.g., building an incident management team, convening regular meetings, issuing weekly reports).

In addition to these planning efforts, Pheonix has also implemented the following:

• An ambitious tree and shade development plan designed to cover a quarter of the city;
• A grant program to fund tree-planting projects in neighborhoods with low shade coverage;
• The Cool Callers Heat Relief Outreach and Heat Relief programs for at-risk residents; and
• The installation of cool pavement in eight city neighborhoods.

In March, the Phoenix City Council passed Ordinance G-7241, which requires all city contractors and subcontractors to have written plans outlining how they will prevent heat-related illnesses and injuries in the workplace. Also, the city’s municipal code chapter 39-5 sets a minimum temperature for cooling and ventilation in rental units. (In related news, the Spokane City Council is considering an ordinance that would guarantee a tenant's right to install and use a "portable cooling device" of their choice.)

King County

Closer to home, several King County departments and partner agencies began working together in 2022 to develop an Extreme Heat Incident Playbook. Rather than relying on temperature alone, the county will use the NWS’ HeatRisk Values scale, which includes how long the heat is expected to stay elevated, how elevated the risk level is for more vulnerable populations, and what time of year the event is expected to take place, since heat events happening outside of normally hot months can take many by surprise.

The county has also added mobile phone emergency alerts to its toolkit, will keep community partners updated via the Community Communications Network, and plans to use kcemergency.com as a hub for resources when an extreme heat event is imminent.

Best Practices for Heat Action Plans

Arsht-Rock and the International Federation of Red Cross and Red Crescent Societies (IFRC) both offer guides for developing heat action plans.

Heat action planning follows the same steps as planning for other potential emergencies: assessing the risk, convening stakeholders, developing interventions and timelines, and regularly reviewing and improving the plan. However, since heatwaves are predictable days or weeks in advance, heat action plans focus more on work to reduce the impact of a heatwave before it occurs.

Both the IFRC and Arsht-Rock emphasize the importance of developing early warning systems that have clearly defined temperature thresholds for issuing heat alerts — including those for at-risk populations — and strong partnerships with healthcare providers and other stakeholders (e.g., nonprofits, schools, libraries, community center, first responders) who can help amplify clear and consistent public messaging leading up to (and during) an event.

External stakeholders are also critical for implementation of heat relief efforts, such as water stations, door-to-door wellness checks, and cooling centers. And, while cooling centers can be a critical component, some agencies are reconsidering where to locate them. A 2023 Grist article on why cooling centers in Portland (OR) and Seattle saw few users during the 2021 heat wave found that a lack of accessibility and transportation contributed to the underuse, but people also described not wanting to be at a public place with strangers for hours with little to do. The latter reason is what has spurred California to focus on developing resilience hubs, not just cooling centers, as part of its 2022 Extreme Heat Action Plan. LAist describes what this looks like in Los Angeles, where the city is working in cooperation with local neighborhood organizations:

These [resilience hubs] are [in] buildings that are already well-used and trusted in a community (…). They’re retrofitted with solar panels and battery power so they can ride out a disaster. They’re chosen by the community and aren’t necessarily run by a government entity.

And, finally, any heat action plan should also consider long-term mitigation strategies, such as cool pavement, tree planting, cool/green roofs, solar canopies, and broad greenhouse gas reduction policies. It may be that your agency is already doing relevant work as part of its climate action plan, and mutual coordination with lead project staff can add the critical heat mitigation component.

Conclusion

While Washington State has traditionally not been known for extreme heat, local governments across the state are beginning to take notice. What the models in Phoenix, Miami, and King County suggest is that a high level of administrative coordination is needed to effectively manage the cross-departmental, cross-organizational efforts to build both the short- and long-term strategies that can protect communities from extreme heat. A centralized system can also raise the level of awareness of the risks (especially in a rapidly warming world) and advocate for funding of mitigation strategies, either by seeking external grants or reallocating existing funds.