July 21, 2023

Multnomah, Washington and Clackamas Counties on Saturday will launch the region’s first joint heat mapping project to record ground-level temperature data. The data will identify what locations regionally are most likely to experience the harmful health effects of rising temperatures. This is the first time a multi-jurisdiction project to collect heat data has been conducted in the Portland metro area. But the effort is one of 17 data collection projects underway nationwide to prepare communities for the increasing threat of extreme heat.

Volunteers will record temperature data while driving designated routes in the three counties at three different times during the day. The temperature data, collected at one-second intervals, will be used to create a detailed area-wide map of local temperatures that take into account the effects of trees, buildings and pavement on neighborhood temperatures. 

The results of the study, expected to be available by the end of 2023, will help inform actions that the three counties and their partners can take to prepare the region as climate change contributes to hotter, drier summers. The public will be able to review the results.

“Extreme heat has proven to be deadly in our community, and it doesn’t stop at county borders,” said Brendon Haggerty, Healthy Homes and Communities program manager for Multnomah County. “Collaborating on this study is one way we can work together as a region to be more prepared for climate hazards.”

Temperatures can be as much as 18 degrees Fahrenheit higher on one city block than a neighboring block due to differences in the amount of pavement and tree canopy. The heat mapping project will help staff from the three counties better understand where and how buildings and other hard surfaces can raise temperatures and limit nighttime cooling, creating urban heat “islands” of higher temperatures relative to outlying areas. 

“As heat waves increase in frequency, duration and magnitude, we know our Black, Indigenous, and people of color neighbors will be disproportionately burdened by climate change,” said Kathleen Johnson, senior environmental health coordinator in Washington County. “Engaging with a variety of stakeholders through collaborative science efforts to find the most effective solutions will help connect those communities with proactive actions.” 

“Data from the heat mapping project will empower our communities with insights into effective strategies to help mitigate heat and extreme weather conditions,” said Dr. Sarah Present, Clackamas County Health Officer. “We can create more resilient communities by improving access to local resources and preserving greenspaces in urban heat islands, rural communities and other areas where they are needed most.”

The counties are partnering with CAPA Strategies, a climate consulting firm that works with municipal governments, non-profits, universities and businesses to describe hyper-local hazards, such as extreme heat, and develop solutions to build resilience and adaptive capacity with and for communities. The National Weather Service is providing additional technical support.

“Using environmental-sensing technologies and analytical techniques gives us the opportunity to improve the information we use for decision-making,” said Joey Williams, manager at CAPA Strategies. “Heat mapping campaigns offer a direct way for communities to take action against rising temperatures in their own neighborhoods.” 

Volunteers will record temperatures across the entire urban area of the three counties, and several populated areas nearby such as Canby, Sandy, Forest Grove and Molalla, that include urban, suburban and rural landscapes. Data will be collected across 41 routes. To collect information, project volunteers will mount sensors on the passenger side of their cars, recording the temperature every second during the one-hour drive times. The volunteers will record temperatures on the same routes three different times, starting at 6 a.m., 3 p.m., and 7 p.m.

The data will also be added to Multnomah County’s Heat Vulnerability Index, a new interactive tool that displays how heat vulnerability, sensitivity, exposure and adaptive capacity differ throughout the area. The tool allows Multnomah County, cities, partner agencies and community-based organizations, including culturally specific and culturally responsive organizations, to make coordinated, geographically targeted outreach efforts to help keep people most at risk safe in their homes. The new data from the heat mapping effort will be used to recalculate the “exposure” score based on the study’s results. 

Increases in emergency medical calls, hospitalizations and mortality

As temperatures become hotter in the tri-county region, emergency medical services calls, hospitalizations and mortality will also continue to increase.

Groups most at risk of health impacts from heat include children, older adults, outdoor workers, low-income households, people who are socially isolated, pregnant women, and people with chronic medical conditions, including cardiovascular disease, diabetes and mental health conditions.