When the heat doesn’t stop
June 30, 2026
Jazmin Castellón stands on Congress Street in Chelsea overlooking a new park, with a pavilion and scattered chairs, beside a flat open area where more trees could potentially be planted. It’s a park she has spent years helping to shape, and when it opens to the public this summer, it will provide shade and relief from the heat for local residents. Along its edges, young trees line the sidewalks every few feet, many just four- or five-years-old. Castellón is the climate justice organizer at Greenroots, a community-based advocacy group, and in her eyes, those trees are crucial infrastructure: a frontline defense against extreme heat.
This type of work is especially urgent in Chelsea, which is one of the hottest cities in Massachusetts. Densely populated, it’s home to many low-income and immigrant residents who face disproportionate exposure to extreme heat. Overcrowded blocks of triple-deckers and apartment buildings leave little room for trees. Pavement, asphalt, and rooftops absorb sunlight during the day and release it slowly at night, trapping heat long after sunset.
Many of the trees in Bear Park were planted thanks to the TreeKeeper program, an initiative Castellón has helped build since 2024. The program trains local residents to care for and expand Chelsea’s urban tree canopy, and has grown into a network of about 80 volunteers maintaining over 200 trees. In neighborhoods where shade is scarce and heat accumulates quickly, the effort has become a critical tool for cooling streets block by block.
More Context
- A climate chief in an era of Trump and energy affordability: Does Melissa Hoffer still get a say? (June 2026)
- Senate energy bill seeks to end contentious gas pipe replacement program (June 2026)
- Average summer temps in Massachusetts have risen by 2.75 degrees Fahrenheit in past 55 years, according to new data (May 2025)
Published by MassINC