The Effect of Trees on Temperature
Urban forests can help keep cities within a healthy temperature range, although the exact temperature reduction from urban forests is difficult to measure. The extent of the effect varies in space and in time, which complicates the issue, but large parks or tracts of urban trees can cool daytime summer air temperatures by about 10°F (McPherson and Simpson 1995).
Increasing the green cover of cities by 10% or more could help temper the local temperature rise projected for coming decades as climate change manifests (Gill et al. 2007).