Summary:

The paper compares thermal conditions of air in July 2014 generating heat stress in the areas with different surface coverage - highly urbanized (center of Bydgoszcz), poorly urbanized (peripheral Fordon district) and used for agriculture (Mochełek). Hourly records of air temperature and humidity, wind speed and total solar radiation meteorological from three automatic weather stations were used for the analysis. We compared the averages and extremes of air temperature and perceptible temperature (temperature of effective radiation TRE). The obtained results showed that in the high building downtown occurred an effect of urban heat island. Air temperature and perceived temperature (TRE) in the center of Bydgoszcz were markedly higher compared to less built-up area and especially in comparison to the rural area. The number of days with heat sensation in Bydgoszcz was twice higher as in the comparable areas: peripheral and rural.