As Seattle continues to work on adopting a tree ordinance, this information mapped in 2020 gives some perspective on the effects of the urban tree canopy. Zooming in on the map, looks like Fremont is one of those heat islands.
From: Trees for Seattle <> Date: Thu, Jul 1, 2021 at 10:16 AM
Subject: Trees for Seattle July Newsletter
“The Results Are In: Urban Heat Mapping Project We all know this last week of June was one of the hottest on record. Were you aware that some areas of King County can be up to 23 degrees hotter than other areas on these hot days? Areas with hotter temperatures in cities are called urban heat islands- these areas typically have less tree canopy , have more asphalt and other impervious surfaces and less tree canopy which contribute to their hotter temperatures.   In 2020, scientists teamed up with residents to collect temperature and humidity data from around King County on one of the hottest days of the summer. The King County and the City of Seattle funded study supported 17 volunteer community scientists who drove 15 routes around the county, taking constant temperature and humidity reading that were used to map heat islands. The maximum temperature the team found that day was 98.8° with a 23.4° difference between the highest and lowest temperatures in the county. A new interactive map helps residents explore how neighborhood temperatures compare across King County.   As we saw this past weekend, the impacts of climate change mean Seattle will continue to face hotter and drier summers. Urban areas are especially prone to high temperatures due to hard surfaces such as buildings and roads, limited vegetation, lack of shade, and heat-producing factors like car use and industrial activity. Urban heat island data helps paint a picture of where tree canopy is needed to help cool and shade these areas. The new map confirmed that hotter areas across King County are primarily in communities of color and places where there are more low-income and elderly people. Already, the Trees for Seattle program has responded to this information by partnering with local organizations to support Duwamish Valley residents (one of the city’s heat islands) in applying for the Trees for Neighborhoods program and receiving up to 4 free trees for their home.”   Urban Heat Map
King County urban heat maps for both afternoon and evening