Microclimate

A microclimate is a local atmospheric zone with a climate differing from the surrounding area. It may be only a square meter, e.g. part of a garden, or square kilometers in size.This is not only a critical factor to account for in sustainable design, but good design also improves the microclimate.

They may be created by:

• bodies of water which cool the air,
• dark colored hard surfaces such as brick, concrete, and asphalt, which absorb solar energy, become hot, and then heat the surrounding air - for example the urban heat island
• landforms which redirect, channel or slow down the prevailing wind.
• slope - South-facing slopes in the Northern Hemisphere and North-facing slopes in the Southern Hemisphere receive more direct sunlight and are thus warmer.
• walls and buildings, which intentionally or accidentally block sun and wind, and sometimes channel wind.

Permaculture and Agroforestry both heavily use microclimates: layers of plants, some Annuals and some Perennials, each need different kinds of environments. Most food forests rely on "guilds" of plants creating microclimates in both the soil and the air environment -- plants that don't want direct sun, can often thrive in the shade of a tree, where they wouldn't otherwise.

A walled garden is a clear example of a microclimate, protected from wind and potentially protected from frost. Walls can retain heat from the sun, and make it easier for warmth oriented plants to survive longer. Designing brick walls for retention, or planting sensitive crops like bananas or coffee near walls can make them better at survivivg

The same forces that make one corner of a garden warmer than another also work at the scale of whole cities. In an urban heat island, roads, roofs and other hard surfaces absorb heat during the day and release it at night, so dense neighbourhoods stay much hotter than the countryside around them. During Delhi's May 2022 heatwave, built-up areas were 2–9 °C hotter than surrounding rural land, and at night up to 20 °C hotter than nearby farmland and forest.^[1] Areas with shade from gardens created cooler spots (shade trees, planting, less bare paving) that even made whole sections of the city cooler: in Delhi, green cover lowers felt temperatures by roughly 5–14%, and native species chosen for the local habitat need less watering.^[1]

Heat risk also depends on who lives in the hottest places. A 2026 study of Pärnu, Estonia, combined satellite temperature data with maps of where older people and young children live, to show where heat is most dangerous.^[2] To see how strong the heat island is in your own city, the Yale Center for Earth Observation's Global Surface UHI Explorer maps satellite-measured daytime and night-time heat island intensity for cities worldwide (2003–2018).

Planners for developing projects can use microclimates to their advantage:

• Less exposed, but sunny areas next to cement, might be perfect for growing plants, or building cold frames, gardens that allow for plants to grow in cold conditions.
• Planting or designing shade into more places, even if it requires artificial structures, might encourage the growth plants or make a space more comfortable for humans and animals
• Adding water to a built environment, can help with passive cooling