Apr 9, 2024 - News

Portland's map of dangerous hotspots

Map of the Portland area with colored lines marking the heat on roads where temperatures were measured

Cars fitted with thermometers drove around Portland on July 22, 2023, to build a picture of hot and cool spots. Screenshot via CAPA Strategies and NIHHIS map

Local officials released a new map showing which parts of Portland are hottest in summer, as they aim to prevent heat deaths like those that killed 69 people in Multnomah County three years ago.

Why it matters: Parts of Portland are more dangerous than others on very hot days, and as the city gets warmer health officials are looking for ways to keep people cool.

Big picture: Heat deaths are down from 2021 when a historic heat dome that June saw a high of 112° — but they are still above average.

  • Five people died of heat-related causes in July and August 2022, which included seven straight days of heat above 95° (from July 25-31).
  • Before 2021, heat deaths in Multnomah County were rare, with no deaths most years and just a single death recorded in 2016 and 2018.

Catch up quick: Multnomah County launched the Heat Vulnerability Index in 2023 to respond to the deadly 2021 heat dome.

  • It uses census data, such as age and income, to show the residents and neighborhoods most at risk from high temperatures.
  • Now the county has added to that a snapshot of temperature data from one day last summer, July 22.

How it works: For a day, volunteers attached thermometers to their cars' passenger windows and drove around the county, sampling air temperatures.

  • After the data collection, environmental consultant CAPA Strategies made maps of the morning, afternoon and evening highs where the cars drove, showing temps at ground level.

By the numbers: The official high that day was 89°, taken at the Portland International Airport.

  • The hottest place was Tualatin (92.1°) and the coolest place was in Forest Park (77.6°).

What they're saying: "For some people that can be the difference between life and death or going to the emergency room, or feeling safe and cool enough in your home," Brendon Haggerty, a manager with the Multnomah County Health Department, told reporters at a press conference last week.

  • Haggerty said not only did the hottest areas have the most concrete and asphalt, but they also had the fewest trees and should be targeted for tree planting and depaving.

What they did: J'reyesha Brannon, an engineer for the city of Portland, was one of the drivers who took readings every few seconds of the ambient (air) temperature and humidity (heat index) across Portland.

  • She said free cooling shelters and air conditioners remain important to "help communities that are hot now and won't be able to wait for canopy to grow."

What's next: The Portland Clean Energy fund directs money toward climate resilience and is on track to fund urban tree planting and distribution of air conditioners.


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