We monitored air and soil temperatures around the Severonikel smelter in Monchegorsk (Kola Peninsula, Northwestern Russia) in 1992-1996. Soil froze in autumn/winter and thawed in spring earlier in heavily polluted industrial barrens than in unpolluted forests. Spring and summer soil temperatures were highest in industrial barrens. During the growth season, air temperatures in heavily polluted sites were either lower tin cool days) or higher tin warm days) than in unpolluted forests. Daily mean air temperatures along the pollution gradient could be estimated from records of meteorological station in Monchegorsk, measurements of pollution load, and altitudes of the study sites. Pollution affected microclimate mostly by altering habitat characteristics, primarily canopy transparency and structure of ground vegetation cover. Pollution-induced changes in temperature regime may increase, mask or compensate toxic effects of pollutants on plants and animals.