Microclimates and Mesoclimates

A microclimate is one that differs from the overall larger scale climate due to the influence of physical characteristics of a local area. A microclimate can be as small as your lawn or as large as a city, river valley, or lake. When the scale of influence is larger, such as a large lake or chain of mountains, the area has a mesoclimate. The scales as applied operationally by meteorologists overlap so that areas the size of river valleys or large cities can fit into either classification.

Factors contributing to the existence of microclimates or mesoclimates include variations in vegetation type, variations in vegetation coverage, soil type, topographic features, lakes and rivers, and exposure to the sun. Urbanization can create a heat island effect. High hills and mountains frequently experience windier and colder conditions. The upwind side of a mountain usually receives more annual precipitation than the downwind side. An exception can occur when a body of water exists on the downwind side and winds occasionally blow off the water. Land adjacent to lakes, oceans, and large rivers will warm slower in the spring and cool slower in the autumn. Numerous examples exist.

Duluth, MN is an excellent example of the influences of hills and lakes on small scale variations of weather and climate. The resulting variation in snowfall within the city and surrounding communities is a worthy study within itself.