Abstract The investigations which have been conducted out for many years permit the statement that in the climate of Poland the occurrence of the UHI is the most important feature of urbanized areas. Over 80% of nights are characterized by surplus heat in towns, amounting to 2–4°C, and sporadically to 8°C and more. A distinct annual course of the UHI intensity is observed; the greatest differences occur during summer nights when skies are clear. In winter, favorable conditions for the existence of the UHI occur less frequently, and the intensity of the UHI is smaller. In the daytime the city is very often colder than its surroundings. Two types of spatial structure of the heat island have been observed: multi-cellular type, occurring on windless conditions (0–1 m/s), and a more simple general type with the 2–4 m/s wind. The distribution of temperature on the night of February 2/3 and 5/6 1996 is presented; the UHI reached an extremely high intensity then (up to 12°C).
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