Urban Heat Island Calculator

Temperature differential from land cover and albedo.

City population

Impervious surface (%)

Tree canopy / green space (%)

Urban albedo (0-1)

Rural albedo (0-1)

Solar radiation (W/m²)

Wind speed (m/s)

Anthropogenic heat (W/m²)

Tab to move between fields

UHI intensity (°C)

4.2

Nighttime UHI (°C)7.14

Summer peak UHI (°C)7.56

Cooling energy increase (%)29.4%

Albedo heating (°C)0.2

Greenspace cooling (°C)0.6

Wind dispersal factor0.69

Cool roof mitigation (°C)0.28

How to Use This Calculator

Enter city population, impervious surface (%), and tree canopy/green space (%).
Set urban and rural albedo values, solar radiation (W/m²), wind speed (m/s), and anthropogenic heat (W/m²).
Review UHI Intensity (°C), Nighttime UHI (°C), and cooling potential from interventions.
Each 10% increase in green space typically reduces UHI intensity by 0.3–0.5°C.

How the result changes with Wind speed (m/s)

City population: City population — larger cities have stronger UHI effect (Oke 1973).
Impervious surface (%): Percentage of land covered by pavement, buildings, and other impervious surfaces.
Tree canopy / green space (%): Percentage of land with tree canopy or vegetated green space.
Urban albedo (0-1): Surface reflectivity: dark asphalt ~0.10, concrete ~0.20, cool roofs ~0.35.
Rural albedo (0-1): Surrounding rural albedo: grassland ~0.25, forest ~0.15, desert ~0.35.
Solar radiation (W/m²): Mean daily incoming solar radiation. ~150 temperate, ~250 tropical.
Wind speed (m/s): Average wind speed — higher winds disperse the heat island.
Anthropogenic heat (W/m²): Waste heat from buildings, vehicles, industry. Typical: 10-50 W/m².

UHI intensity (°C): Average urban-rural temperature differential.
Nighttime UHI (°C): Nighttime UHI is typically 1.5-2× daytime due to thermal mass release.
Summer peak UHI (°C): Peak summer UHI intensity.
Cooling energy increase (%): Estimated increase in cooling energy demand from UHI.
Albedo heating (°C): Temperature contribution from urban-rural albedo difference.
Greenspace cooling (°C): Cooling provided by vegetation and evapotranspiration.
Wind dispersal factor: Wind speed reduction factor on UHI (1.0 = calm, lower = more dispersal).
Cool roof mitigation (°C): Potential UHI reduction if urban albedo increased to 0.35 (cool roofs).

Identify Input Parameters
4 parameters
City population = 500000, Impervious surface (%) = 60, Tree canopy / green space (%) = 15, Urban albedo (0-1) = 0.15 = 8 input(s) provided
Calculate UHI intensity
UHI intensity
4.2 = 4.2
Calculate Nighttime UHI
Nighttime UHI = uhiIntensity * 1.7
7.14 = 7.14
Calculate Summer peak UHI
Summer peak UHI = uhiIntensity * 1.8
7.56 = 7.56