Do urban trees cool parks differently by time?

Tree layout changes cooling by day and night

New research from Concordia University finds that the cooling benefits of urban parks are not uniform across the day. Instead, the arrangement of trees within a park can change how well different areas are cooled at daytime versus nighttime.

The study’s core idea is that urban microclimates are dynamic. During the day, shade and evapotranspiration from vegetation can reduce surface and air temperatures. At night, however, cooling depends heavily on how heat is released from surfaces and how air can move—factors that can differ substantially depending on canopy coverage, spacing, and park geometry.

Because tree placement influences these processes, researchers concluded that park design choices—such as how trees are positioned and how densely they’re arranged—affect cooling performance differently by time of day.

This matters for cities planning heat adaptation. Many municipalities treat “park cooling” as a single headline benefit, but residents experience heat exposure in shifts: hot afternoons and warm nights both affect health, sleep, and the risk of heat stress.

The findings suggest that planners may need to treat park vegetation design as a tool for tailoring cooling outcomes across the daily cycle, not just maximizing midday shade. If nighttime cooling is weaker than expected, vulnerable areas—especially those near residences—may continue to experience high temperatures after sunset.

What to take away

• Tree arrangement can influence microclimates differently during day versus night.
• Heat adaptation strategies should consider daily timing, not only average cooling.
• Urban forestry and park design may need optimization for nighttime comfort and health benefits.