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High temperatures bring citizen scientists to map the hottest places in D.C. and Baltimore
Monica Allen
/ Categories: Research Headlines, Climate

High temperatures bring citizen scientists to map the hottest places in D.C. and Baltimore

With the Mid-Atlantic region expecting a stretch of days with above-normal summer temperatures,  NOAA and its partners will lead a group of citizen scientist volunteers on a mission this week to collect data that will be used to map the hottest places in Washington, D.C. and Baltimore.

The research is led by an urban studies professor from Portland State University, a climate scientist from the Science Museum of Virginia and several community partners, with funding from NOAA’s Climate Program Office.

Using specially designed thermal sensors mounted on their cars, the volunteers will drive prescribed pathways through the city, recording temperature once per second along with the exact time and location of each measurement.  The goal is to produce highly detailed maps of both cities’ urban heat islands — areas within a city that can run 10 to 20 degrees hotter than other areas.  The term “urban heat islands” refers to the fact that cities’ unshaded roads and buildings absorb more heat during the day and radiate that heat back into the surrounding air, significantly increasing the local air temperature relative to more vegetated or shaded areas.  On days when local temperatures climb above 95 degrees F, the additional heat emitted by paved and concrete structures can produce dangerously hot areas within specific city neighborhoods. 

Planning heat island research

Planning heat island research

Jeremy Hoffman of the Science Museum of Virginia, left, and Vivek Shandas of Portland State University, plan the routes that volunteers will take to map heat islands in Richmond, Virginia. Courtesy of Jeremy Hoffman

Volunteers collect data on ‘heat islands’

“By measuring temperatures in tens of thousands of locations throughout a city, we can map what areas are hottest, and the reason behind those patterns,” explained Vivek Shandas, a professor at Portland State University. “It’s a very simple system that any city can use to describe the urban heat island effect, which can help to inform planning strategies to cool the city, especially in areas where the most vulnerable populations live.”  

With the resulting maps, city officials can overlay their location-specific heat data with other local data such as population demographics, health records, air quality data, and local landscape features like roads, buildings, and trees—information that can help to mitigate negative health impacts of extreme heat.  Urban heat islands have a two-fold effect on health.  Extreme heat poses elevated risks of dehydration and other heat-related illnesses, especially for elderly, homeless, and low-income communities; and it can also increase the prevalence of air pollution and smog, threatening complications for people who have respiratory conditions like asthma.

Heat island maps helping Richmond

 “Last summer, our citizen science campaign found a 16 degree F difference between the warmest and coolest spots in Richmond,” said Jeremy Hoffman, climate scientist and co-principal investigator from the Science Museum of Virginia.  “Comparing our data with data from the Virginia Department of Health and the Richmond Ambulance Authority, we see that the highest rates of heat-related illnesses are concentrated in the areas with the highest temperatures. This has helped our city government, local nonprofits, and private citizens collaboratively prioritize where to take immediate action on extreme heat.”

Seeking hot spots

Seeking hot spots

Youth from Groundwork RVA join with Jeremy Hoffman to look for hot spots in Richmond, Virginia, using a forward-looking infrared thermal camera. Courtesy of Jeremy Hoffman

According to NOAA climate data, Washington, D.C., has historically experienced about 5 days per year in which temperature climbed above 95 degrees F, on average, and Baltimore experienced about 8 days per year above 95 degrees F. 

“Climate models project that the average number of days above 95 in those cities could more than double by the year 2030,” said David Herring, of NOAA’s Climate Program Office.  “That number might increase to 40 by the year 2060; and to 80 days or more by 2100.  Imagine a future in which D.C. and Baltimore residents experience between 40 and 80 days per year exposed to dangerously high temperatures.”    

Cooling ideas for cities

But it doesn’t have to be that way, said Shandas. “With these new, detailed maps of the cities’ urban heat islands, citizens and city officials can examine the extent to which specific interventions can be applied to existing and new buildings across different land uses.”  Such strategies may include opening more public air-conditioned spaces, removing or whitewashing large areas of black asphalt or roof surfaces, adding more trees, and requiring developers to vary the heights of new buildings to increase natural airflow in hot neighborhoods.

“Another goal of our team moving forward is to develop an off-the-shelf, ready-made template for other cities around the country to affordably conduct urban heat island mapping campaigns,” Shandas added.

“And by building a collaborative network composed of city residents, local science centers and universities, and environmental or community non-profits,” said Hoffman, “any city in the country can take the first steps to address their exposure to extreme heat and start building resilience to climate hazards.” 

According to Hoffman, relationships with and coordination between local organizations is key to the project’s success.  “The National Aquarium in Baltimore and Casey Trees, a D.C.-based non-profit, have been particularly helpful in recruiting local volunteers and providing a basecamp of operations in both cities, and will champion these data in their ongoing work with public and stakeholder audiences, going forward.”

For more information, please contact Monica Allen, NOAA Communications, at 301-734-1123 or


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