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