Location of first occurrence of a tropical day

Map shows locations, where the first tropical day in a year was observed in the Czech Republic, in the period from 1961 to 2020. The number of first occurrence at a particular location is represented by the point color and size. Given that the first tropical day in a year can be observed at more than one station on the same day, the number of occurrences is higher than the number of years in the period of interest. The assessment includes 133 stations in the Czech Republic with a sufficiently long data series.