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Urban Heat Island Estimate Calculator

Work out urban heat island estimate instantly with clear inputs, formula shown and shareable results.

About Urban Heat Island Estimate Calculator

Oke's empirical relation gives maximum urban heat island intensity as 2.01 log10(population) - 4.06 degrees for calm clear nights. Green cover reduces it through evapotranspiration and shading, a low sky view factor increases it by trapping radiated heat, and wind mixes the urban boundary layer and suppresses it.

Formulas

Population baseline

ΔT max = 2.01 log10(population) - 4.06 °C for calm clear conditions

Adjustments

Reduced by green cover and wind, increased where sky view factor is low

Worked example

With the default values below, Urban Heat Island Estimate Calculator returns Estimated heat island intensity of 5.67. Change any input above and every figure here is recalculated in your browser.

Inputs used

Urban populationminimum 100
500,000
Green coveraccepts 0–80 %
15 %
Average sky view factoraccepts 0.05–1
0.55
Average wind speedminimum 0.1 m/s
2 m/s

Results

Estimated heat island intensity
5.67 °C
Population based baseline
7.39 °C
Reduction from green cover
0.55 °C
Assessment
Severe heat island, significant health and cooling load implications

Step by step

  1. 1Values used
  2. 2Population baseline
  3. 3Adjustments
  4. 4Estimated heat island intensity= 5.67 °C
  5. 5Population based baseline= 7.39 °C
  6. 6Reduction from green cover= 0.55 °C
  7. 7Assessment= Severe heat island, significant health and cooling load implications

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Urban Heat Island Estimate figure worked out?

ΔT max = 2.01 log10(population) - 4.06 °C for calm clear conditions. Oke's empirical relation gives maximum urban heat island intensity as 2.01 log10(population) - 4.06 degrees for calm clear nights.

Why is the heat island strongest at night?

During the day evaporation and mixing dominate. At night rural surfaces cool rapidly by radiation while urban surfaces release stored heat and cannot see the sky, so the difference peaks a few hours after sunset.

What values do I need to enter?

This calculator takes 4 inputs: Urban population, Green cover, Average sky view factor, Average wind speed. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.

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