Wisconsin Heat Vulnerability Index (HVI)

Analysis of 60 years of weather data by the Wisconsin Initiative on Climate Change Impacts (WICCI) indicates that Wisconsin has become warmer. Across the upper Midwest, temperatures were notably high in 2012. Extreme heat is known to have negative impacts (related to death and illness) on human health. Extreme heat can disproportionately affect vulnerable populations such as elderly populations, socially isolated people, and those with pre-existing chronic conditions such as cardiovascular disease. These risk factors allow us to pinpoint the vulnerable populations in our community.

This project used existing population and census data, natural and built environment data, and health factors data to create a heat vulnerability index (HVI) to identify areas of greatest risk for negative health impacts due to extreme heat in the entire state of Wisconsin and the greater Milwaukee urban area. Listed below are the specific indicators that were used in the analysis. The maps can help identify high-risk neighborhoods and populations to receive targeted messaging related to heat events and additional resources during extreme heat events.

View an image of the Wisconsin Heat Vulnerability Index (HVI) Map

View the Milwaukee Heat Vulnerability Index (HVI) Map (PDF, 2.3 MB)

For more detailed information and analysis, view our reports on the Wisconsin Heat Vulnerability Index (PDF, 1.2 MB) and the Milwaukee Heat Vulnerability Index (PDF, 1.2 MB)

County-specific HVI maps exist for all counties in Wisconsin.

Indicators included in the Wisconsin Heat Vulnerability Index

Using methodology developed by the San Francisco Department of Public Health, the Wisconsin Building Resilience Against Climate Effects (BRACE) staff conducted a geo-spatial analysis of heat-related vulnerability in both Wisconsin as a whole and the greater Milwaukee urban area, with assistance from the Wisconsin Department of Health Services (DHS) Bureau of Information Technology Services.

Further analysis that helped identify how different indicators affected the analysis included separating out each of the four categories of indicators: population density, health factors, natural and built environment, and demographic and socioeconomic factors.

Population Density

  • Population per square mile

Health Factors

  • Diabetes prevalence*
  • Adult asthma prevalence*
  • Hypertension rate*
  • Percentage of population obese (BMI)*
  • Percentage uninsured*
  • Percentage of population receiving public substance abuse services*
  • Percentage of population receiving public mental health services
  • Percentage of population that visited an emergency department for heat stress

Demographic and Socioeconomic Factors

  • Percentage of households in poverty
  • Percentage of population aged 0-4
  • Percentage of population aged 85+
  • Percentage of population living alone
  • Percentage of population 65+ living alone
  • Percentage of non-white population
  • Percentage of population with less than high school education

Natural and Built Environment

  • July 6, 2012 temperature (hottest day of 2012)
  • July 2012, average PM 2.5 concentration (ug/m3)
  • July 2012, maximum recorded ozone level (ppb)
  • Percentage of households without a vehicle
  • Medium- and high-density land cover classification
  • Nursing home bed count

* Indicators used only in statewide map because collected at county level


County HVI Maps

County-specific heat vulnerability index (HVI) maps were created for the entire state of Wisconsin. The data displayed in the maps are meant to serve as an informational tool to better understand the spatial distribution of human populations most vulnerable to extreme heat-related events.

The county-specific maps are based on the statewide Wisconsin Heat Vulnerability Index, but have a reduced number of health-related indicators. Each county map is representative of that county, and is not comparable to maps for other counties in Wisconsin.

Counties A-H





Counties I-P

Counties R-Z



Last Revised: February 23, 2016