More Accurate Heat Mapping & Tree Planting In Philadelphia

Temperatures in neighborhoods with lower tree canopy coverage soared as much as 10.5˚ higher than more tree-dense areas at the same time of day.


Heat MapA new high-resolution heat map of Philadelphia, PA from The Nature Conservancy (TNC) more closely resembles the actual heat people feel on a hot urban summer day—and reveals how local landscape features affect temperature and humidity.

The data for the new heat map was gathered in the summer of 2022 when multiple partner organizations—including the Pennsylvania Horticultural Society (PHS), community groups, and city residents—mapped Philadelphia’s “urban heat island” as part of a federally-funded study to uncover how heat varies across neighborhoods on a hot summer day.

The measurements taken during this campaign notably differ from those used in previous heat maps, however, due to more “real world” methodology. In prior heat maps, temperatures were obtained by satellites recording surface temperatures, like the tops of buildings. Yet this campaign measured air temperature and humidity close to the ground, more closely representing the heat people feel. Additionally, measurements were collected at multiple times of day (morning, afternoon, and evening), capturing how the hottest and coolest areas change depending on time of day.

The findings from TNC’s study, dubbed the Citywide Heat Ride, revealed that temperatures in neighborhoods with lower tree canopy coverage soared as much as 10.5˚ higher than more tree-dense areas at the same time of day, underscoring the importance of increasing the level of tree canopy coverage, especially in areas with high vulnerability to extreme heat.

Lori Brennan, executive director of TNC in Pennsylvania and Delaware, emphasized the significance of this study, stating, “As average temperatures continue to rise due to a changing climate, it’s more critical than ever to employ nature-based solutions in our communities.”

heat map
Last month, PECO employees volunteered with PHS to help unload and sort trees that were planted across the Philadelphia region. PECO has a ReLeaf mission to plant one tree for every tree removed.

PHS is doing its part to answer this call. Last month, PHS and over 90 Tree Tenders groups, community organizations, and neighborhood volunteers came together to plant 1,770 trees throughout the Greater Philadelphia region as part of its More Trees Please” campaign. This semi-annual event, held each Spring and Fall, is a core component of PHS’s mission to create healthier, greener communities. The program not only enhances the tree canopy but also fosters social connections and community engagement. Monetary donations to the campaign can be made year-round by clicking here.

This article was adapted from a PHS Blog article by Melissa O’Brien.


For more articles on tree planting, read:

Emerging Tech Addresses Root Girdling

Staking Trees For Better Outcomes

Assessing Trees For Storm Resilience


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