Probability values for the intensity of Barcelona's urban heat island (Spain)

Based upon the daily minimum temperatures provided by Barcelona's official weather stations and its airport for a ten-year period (2004-2013), these daily differences were calculated as an indicator of the average intensity of the heat island, estimated to be approximately 2 degrees C. With the use of the best-fit probability distributions from the statistical package EasyFit, the probability values for intensities of the heat island equal to, or greater than, 1 degrees C, 2 degrees C, 3 degrees C, 4 degrees C, etc. were calculated for the whole period, according to seasons and to months. The highest intensities are recorded in autumn and winter and the lowest ones in summer. In each of the first two seasons, a night with an intensity equal to, or exceeding, 7 degrees C can be expected every one thousand days, i.e. once just over every 10 years. With the reference of a study on this city from the 1980s, the intensity of Barcelona's heat island shows a slight decrease, a fact that can be associated with the stagnation of the city and a certain population decrease therein and in the neighbouring municipalities. Nonetheless, the negative effects thereof on human health have been aggravated as a result of global warming.