Urban green spaces can reduce urban air temperature through evapotranspiration. The rate of evapotranspiration, thus the air temperature cooling, may be limited by low soil moisture content if the urban green space is unirrigated in summer.

This study aimed to investigate whether irrigating a small urban green space can increase its cooling effect. The microclimate of an irrigated turfgrass plot (4 mm/day) was directly compared to an unirrigated turfgrass plot (6×6 m²). Irrigation was applied at 13:00 local time for six weeks. In Week 6, the 4-mm irrigation reduced daytime soil temperature, turf surface temperature, air temperature and universal thermal climate index by 1.7, 2.3, 0.6 and 0.4 ^◦C, respectively.

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All daytime impacts were statistically significant. The findings suggested that irrigating small urban green spaces can reduce air temperature but not human heat stress. Irrigation has the potential to significantly improve the thermal conditions of small green spaces in combination with the use of tree shade.