Portland Metro 2023 Heat Watch Report: A Summary of Results

On July 22nd, 2023 more than 100 volunteers partnered with County staff and CAPA Strategies. 

Their purpose that day was to map differences in temperature throughout the region. They mapped neighborhoods across Clackamas, Multnomah and Washington Counties.

Volunteers attached special equipment to their cars and collected thousands of temperature readings. The result is a new tool for understanding how heat impacts our communities. Each county is working to protect community health from climate change impacts. This project is part of these strategic efforts.

The information has now been published in the Portland Metro Region Heat Watch Report.

Why It’s Important to Understand Heat in Our Community

Extreme heat is dangerous and climate change is making it more likely that our region will experience events like the 2021 heat dome. Some groups are more at risk for serious health effects from heat.

• Children
• Older adults
• Pregnant people
• Outdoor workers
• Low-income households
• Athletes who exercise outdoors
• People living unsheltered or homeless
• People who are socially isolated
• People with certain medical conditions
• People who are taking certain medications

Health effects from heat include:

• Heat stroke
• Breathing problems
• Heart trouble
• Pregnancy complications

If we understand which areas in our region get hottest we can help the people who live and work in them. We can improve neighborhoods by improvements in:

• Emergency response
• City planning
• Healthcare
• Public health

Collecting the Temperature Data

It was a hot, clear day when teams of volunteers collected the data. They drove along planned routes throughout Clackamas, Multnomah, and Washington counties. Each team of volunteers had a sensor on their car that collected data as they drove.

• The sensors collected thousands of measurements. This included air temperature, humidity (the amount of water in the air), and the car’s location and speed.
• Other cities have used the same method, but the Portland metro campaign is the largest in the world to date.

Important Results

The data makes it clear that heat is not experienced equally across our region. Across the Portland metro region, there was a 17 degree Fahrenheit difference between the hottest and coolest places. That is a big difference!

• Clackamas County’s hottest cities included Molalla, Canby, and Wilsonville.
• Multnomah County’s hottest cities included Wood Village, Maywood Park and Fairview. The hottest areas are near Lents, Mall 205, and industrial areas near Portland International Airport.
• Washington County’s hottest areas include parts of Sherwood, Tualatin, and Cornelius.

The hottest areas were mostly suburban cities near highways. These areas have similar attributes.

• Fewer trees
• More hard surfaces (like roads, rooftops and parking lots)
• Sprawling development patterns

The coolest areas were parks and rural forested areas.

How This Data Will be Used

• All three counties are working together, along with healthcare systems, to help areas with high heat become safer over time.
• The data informs decisions about land use planning, transportation, housing and tree planting.
• Healthcare and outreach workers will use this information to support people who are most at risk during extreme heat.
• Clackamas County will use this information to inform their Climate Adaptation plan, Natural Hazard Mitigation plan and other emergency response plans to reduce impacts of extreme heat on employees, community members, and visitors.
• Multnomah County will update their Heat Vulnerability Index (HVI) with this information.
• Washington County will use this information to inform their Climate Adaptation plan and emergency response plans for extreme heat.

What You Can Do to Protect Yourself and Your Community from Extreme Heat

Stay Informed

Sign up for public alerts

Take Heat Safety Seriously

When it’s hot, take care of yourself by drinking water, avoiding strenuous outdoor activities during peak heat hours, and knowing the signs of heat illness. Learn more from the CDC’s Tips for Preventing Heat-Related Illness.

Support Your Neighbors

Check on your neighbors during a heatwave to make sure they stay safe and cool. In particular, think about those who are:

• Living alone
• Without air conditioning
• Living with a chronic illness
• A part of another vulnerable group

Neighbors helping neighbors is the best way to keep us all safe.

Prepare

Prepare an emergency kit for heat-related emergencies.

• Water
• Non-perishable food
• Medications
• First aid supplies

Make a plan to keep your home cool or find an air conditioned space. There are resources for households who need low-cost air conditioning. Check with your healthcare provider, utilities and local governments.

Create Cool Spaces

Take steps to create cool spaces within your home.

• Use fans (when below 95 degrees Fahrenheit)
• Close curtains or blinds during the hottest part of the day
• Improve airflow by opening windows during cooler parts of the day