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Mississauga, Ontario | Climate resilience

Heat Risk in Mississauga

Using GIS to identify priority areas for community heat response

This project combines land-surface temperature, Census-based social vulnerability, and mapped cooling-resource density to identify where heat-response concerns overlap.

  • Community planning
  • Spatial analysis
  • Static case study
  • ArcGIS Pro
  • Landsat 8
  • Statistics Canada Census
  • City of Mississauga Open Data
Key insight The hottest areas are not always the most socially vulnerable. Priority attention is needed where heat exposure, social vulnerability, and limited cooling support overlap.
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Final heat-response priority screening map for Mississauga Census Tracts, with red tracts showing all three selected concerns.
Final heat-response priority screening map showing where selected heat-response concerns overlap by Census Tract.

Where should heat-response attention be considered first?

Research question: Where do higher urban heat exposure, greater social vulnerability, and lower cooling-resource density overlap in Mississauga?

This citywide screening tool identifies Census Tracts where multiple concerns coincide, helping focus local assessment, outreach, cooling services, shade, and greening reviews.

Screening noteThis is a screening tool. It is not a prediction of heat illness and does not establish direct causation.

Three-component heat-response screening framework

Heat exposureLandsat land-surface temperature
Social vulnerabilityCensus-based relative score
Limited cooling supportLow mapped resource density
Heat-response priority screening

Heat exposure

Landsat 8 surface-temperature data from 14 August 2024 were clipped to Mississauga and converted to degrees Celsius. Zonal statistics then summarized mean land-surface temperature for each Census Tract.

The raster shows local hot and cool surfaces. The Census Tract version supports comparison with Census and cooling-resource layers, but it smooths smaller hot spots.

Land-surface temperature raster

Landsat-derived land-surface temperature raster clipped to Mississauga on August 14, 2024.
Local surface-temperature pattern before Census Tract aggregation.

Mean land-surface temperature by Census Tract

Map of mean land-surface temperature by Mississauga Census Tract using zonal statistics.
Mean LST by tract for comparison with vulnerability and cooling-resource data.
CaveatLand-surface temperature is not air temperature. It measures the temperature of ground and built surfaces at the time of satellite acquisition.

Social vulnerability

Seven Census indicators were converted to comparable percentile ranks and averaged into a relative planning score. The result is not a count or percentage of all vulnerable residents.

Social vulnerability map for Mississauga Census Tracts using a percentile-based vulnerability score.
Relative social-vulnerability score by Census Tract.

Indicators

  • Residents aged 65 and older
  • Children aged 0 to 14
  • Renter households
  • Apartment dwellings
  • Low-income residents
  • One-person households
  • Households in core housing need
Raw Census values Percentages using appropriate denominators Percentile rank across 147 Census Tracts Average of seven percentile ranks Relative social-vulnerability score
Method note

Percentage = indicator count divided by the appropriate population, household, or dwelling denominator, multiplied by 100.

Percentile rank = the relative position of that percentage among the 147 Mississauga Census Tracts.

The indicators overlap and use different units: people, households, and dwellings. Adding them would double-count some residents and mix incompatible units. Percentile ranking keeps the indicators comparable without treating them as a count of unique vulnerable residents.

Mapped cooling support

Mapped cooling options were counted within each Census Tract and divided by tract land area. The result is a density-based screening proxy, not a full accessibility model.

  • Community centres
  • Libraries
  • Municipal pools
  • Spray pads
  • Parks
  • Shade structures

Cooling-resource locations

Map of mapped public cooling-resource locations in Mississauga, including parks, shade structures, spray pads, municipal pools, libraries, and community centres.
Public cooling-resource locations used in the tract summary.

Cooling options per square kilometre

Map of mapped cooling options per square kilometre by Mississauga Census Tract.
Cooling options per square kilometre by Census Tract.
Interpretation noteCooling-resource density does not measure facility capacity, opening hours, shade quality, accessibility, walking distance, transit access, or service quality.

Heat-response priority screening

After the three inputs were prepared, each Census Tract received one point for each concern it met:

  • High social vulnerability: vulnerability score greater than or equal to 60
  • Higher heat exposure: mean LST greater than or equal to 37.1°C
  • Lower cooling-resource density: low-cooling score greater than or equal to 60
Heat-response priority screening map for Mississauga showing Census Tracts by number of selected concerns met.
Red tracts meet all three criteria and should be reviewed first for local assessment. This is a screening result, not a prediction of heat illness.
  • Red: all three concerns
  • Orange: two concerns
  • Yellow: one concern
  • Grey: no selected concern

Analytical workflow

  1. USGS Landsat 8, Statistics Canada Census, and City of Mississauga Open Data
  2. Clip and filter to Mississauga
  3. Standardize analysis to 147 Census Tracts
  4. Calculate mean LST, build social-vulnerability score, and calculate cooling-resource density
  5. Apply screening thresholds
  6. Count concerns from zero to three
  7. Heat-response priority screening map

Key findings

Heat exposure and social vulnerability do not perfectly overlap.

Some of the hottest Census Tracts are not the same places as the highest-vulnerability Census Tracts.

Mapped cooling support is uneven.

Some Census Tracts contain few or no mapped options per square kilometre while neighbouring tracts contain more resources.

Priority tracts require local validation.

Score-3 tracts should be examined first for indoor cooling access, hours, capacity, shade, walkability, transit, outreach, and greening opportunities.

How the analysis could support planning

The screening map identifies where closer assessment may be useful, not which intervention must be implemented.

  • Heat-response outreach
  • Temporary cooling hubs
  • Indoor cooling access
  • Shade assessments
  • Greening opportunities
  • Transit and walking-access analysis
  • Facility-capacity review
  • Community consultation

Limitations

  • The Landsat image represents one acquisition date rather than long-term heat conditions.
  • Land-surface temperature is different from air temperature.
  • Census Tract averages smooth local variation and smaller hot spots.
  • The social-vulnerability index is relative within Mississauga.
  • The vulnerability index is not a count of unique vulnerable residents.
  • Cooling-resource density does not represent capacity, opening hours, quality, accessibility, or walking time.
  • The source datasets represent different years: 2021 Census, 2024 Landsat, and 2026 cooling-resource data.
  • Threshold choices affect which Census Tracts are selected.
  • The final map is a screening output rather than a causal model or health-risk prediction.

Tools and methods

Tools

  • ArcGIS Pro
  • Landsat 8 Collection 2 Level-2 Surface Temperature
  • Statistics Canada 2021 Census
  • City of Mississauga Open Data

GIS methods

  • Raster clipping
  • Surface-temperature conversion
  • Zonal statistics
  • Census data joins
  • Percentage calculation
  • Percentile ranking
  • Composite vulnerability scoring
  • Point-in-polygon summarization
  • Density calculation
  • Natural Breaks classification
  • Multi-criteria screening
  • Cartographic design

Data sources

  • USGS Landsat 8 surface-temperature data, 14 August 2024
  • Statistics Canada 2021 Census
  • Statistics Canada Census Tract geography
  • City of Mississauga municipal boundary
  • City of Mississauga Open Data cooling-resource locations

Reasonable next steps

  • Use multiple cloud-free summer scenes instead of one acquisition date.
  • Compare surface temperature across several dates or years.
  • Add tree canopy and impervious-surface data if appropriate source data is obtained.
  • Model walking or transit access to cooling facilities.
  • Include facility hours, capacity, accessibility, and service quality.
  • Validate priority areas through local assessment and community consultation.
  • Review how alternative thresholds affect the screening result.

Downloads

Project presentation PDF Final priority map WebP

Raw and derived datasets are not published here because licensing and redistribution permissions should be confirmed first.

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