Urban Heat Island

What is an urban heat island?

An urban heat island (UHI) is an urban area that is significantly warmer than its surrounding rural areas. Modified land surfaces (paving, sidewalks, streets, etc.) in the urban environment retain heat and are the main cause of UHI. 

In Fredericksburg, the UHI is strongest in the summer months. When combined with summer weather, the UHI can create periods of extremely high temperatures and humidity levels that have serious health impacts on vulnerable members of our community (people with asthma and pulmonary conditions, the elderly, etc.). As extreme heat events increase with climate change, the urban heat island is projected to intensify. 

How do higher temperatures from urban heat islands impact our community?

  • Negatively affect our health and comfort 
  • Elevate level of air pollutants and greenhouse gas emissions
  • Higher energy bills 
  • Increase energy consumption in buildings
  • Impair water quality

What can you do to reduce the impact of UHIs?

  • Plant trees or care for trees in your neighborhood
  • Install a vegetated or green roof
  • Create a green space on vacant land or help maintain an existing green space 
  • Install permeable surfaces on roadways, sidewalks, parking lots, and alleys

Urban Heat Island (UHI) Effects in Fredericksburg, VA


The urban heat island effect, which describes when urban areas are significantly warmer than their rural counterparts, highlights areas where people may be more at risk of death or hospitalization. As temperatures rise, urban heat islands are expected to become more prevalent as cities contain more heat-absorbing asphalt and less cooling tree canopy. While most research has focused on larger cities and their redlined communities, we are interested in understanding urban heat vulnerability within smaller cities. Fredericksburg, Virginia is an ideal location to study extreme heat in a small city as it contains both an urbanized historical downtown district with suburban-like neighborhoods surrounding the downtown. We first created a heat vulnerability rating for each census block group in the city using social, environmental, and health data. Average neighborhood temperatures were calculated for each neighborhood using land surface temperature data, from the LANDSAT 8 satellite, and air temperature data, collected by volunteers, using PocketLab Weathers. We were then able to compare vulnerability to heat to measure if those who were most vulnerable to heat in the city actually were exposed to higher temperatures. We find that overall, the most vulnerable neighborhoods are significantly warmer (by 3.03°C on average) than the least vulnerable neighborhoods.

Citation: Spencer, A; Grothe, P. Comparing Social and Environmental Vulnerability Indexes to Summer Heat in Fredericksburg, VA; Journal of Virginia Science. (In Prep)

Stay Cool and Safe!

The City of Fredericksburg opens cooling stations when the temperature and/or heat index is expected to reach or exceed 95°F.

For more information regarding cooling assistance services, city residents should contact the City’s Department of Social Services at (540) 372-1032. In the event of a heat related emergency, please call 9-1-1.

Virginia’s Cooling Assistance Program is available to households with a child under six years old, a person with disabilities, or an adult age 60 or older living in the home who meet the program’s income and eligibility requirements.