Key Data Builds on National Research to Inform Community Responses to Rising Summer Temperatures

BOSTON, MA – This week, the Museum of Science, Boston, the Mystic River Watershed Association (MyRWA), and the Town of Arlington announced the results of “Wicked Hot Mystic,” a research project that developed detailed heat maps that bring to light how extreme heat impacts neighborhoods differently. In partnership with Resilient Mystic Collaborative communities, the Metropolitan Area Planning Council (MAPC), GreenRoots, and over 80 volunteers, the results of Wicked Hot Mystic will inform future climate resiliency planning and improve equitable outcomes in climate-vulnerable populations along the Mystic River.

The analysis of the data collected during a summer 2021 heat wave by volunteer scientists found direct correlations between air temperature and land use, race, and income within the Mystic River Watershed, the most highly urbanized watershed in New England. Areas with more tree cover, green space, and nearby water were up to ten degrees cooler than those with more pavement and concrete. The resulting heat maps will be available on the MAPC website and

The hottest neighborhoods were in Chelsea, Somerville, East Boston, Everett, Revere, and Charlestown, and were up to 10 degrees F hotter than the coolest areas in the watershed.  Further, the data revealed that the highest modeled air temperature value within the watershed was along Mystic Avenue in Somerville at 97.4 F, with a heat index of 100.7 F.

Neighborhood temperatures correlated strongly with historic redlining maps, a racist federal housing policy that excluded predominantly Black, immigrant, and religious minority communities from securing mortgages, reinforcing residential segregation. Nearly a century later, the legacy of this divestment is still clearly visible in Greater Boston. The Wicked Hot Mystic research team found that primarily white neighborhoods have up to 43% tree cover versus just 3% tree cover in BIPOC neighborhoods, which experienced temperatures nearly four degrees hotter at the same time.

Extreme heat events and the resulting urban heat island effect are increasingly critical occurrences burdening society to which public health workers respond. Studies show that 911 call volume increases during heat waves. The hotter temperatures can adversely affect people living with respiratory and cardiac illnesses, and people unable to escape the heat.

“As summer temperatures get hotter each year, the implementation of resiliency solutions becomes ever more imperative to ensure the equitable health of all communities,” said David Sittenfeld, manager of forums, national collaborations, and current science communication at the Museum of Science. “The Wicked Hot Mystic research, collected by volunteers living in the watershed, will be a powerful tool for cities and towns throughout the Watershed to address the harmful effects of extreme heat and improve the vitality of all neighborhoods.”

“When blizzards hit Greater Boston, we’re ready.  We know what to do to stay safe, and rarely do people die,” said Melanie Gárate, MyRWA’s climate resilience manager. “We need to become a heat wave culture so that individuals and leaders know what to do to keep communities safe during extreme temperatures.”

“Racist federal mortgage policies called “redlining” from nearly a century ago led to lasting segregation and economic disinvestment in communities of color,” said Bianca Bowman, climate justice organizer for GreenRoots. “Public policy led to our BIPOC neighbors being disproportionately in harm’s way, and ongoing racism, disinvestment, and a lack of amenities like trees in these same Environmental Justice communities continue to have a negative impact. Our climate policies and investments need to focus on righting these wrongs as heatwaves increasingly characterize Greater Boston’s summers, impacting disenfranchised residents the most.”

The Wicked Hot Mystic research builds upon the 2019 Wicked Hot Boston study, led by the Museum of Science in partnership with Northeastern University, CAPA Strategies, and the communities of Boston, Cambridge, and Brookline, as part of a national heat mapping campaign through the National Oceanic and Atmospheric Administration (NOAA). For more information on the Wicked Hot Mystic project, visit