The paper analyzes trends in the extreme temperature indices based on fixed thresholds
in Bosnia and Herzegovina during the 1961–2016. Based on data from 12 meteorological stations,
trends in both warm and cold temperature indices were determined using the nonparametric Mann-
Kendall test and the nonparametric Sen’s slope estimator. The observed tendencies in indices
based on fixed thresholds were as expected in a warming world – warm temperature indices
(summer days, tropical days and tropical nights) displayed the significant positive trends, whereas
cold temperature indices (icing days and frost days) showed the downward tendencies. The annual
occurrence of summer days and tropical days increased on average for 5.3 and 4.8 days per
decade, respectively, whereas icing days and frost days displayed downward trends in the range of
-1.7 and -3.6 days per decade, respectively. The obtained results indicate that the climate system
warming was more a result of very pronounced positive trends in the warm temperature indices
than the downward tendency of cold ones. The most prominent changes were observed in Banja
Luka, Bugojno and Zenica regions. Both trends, positive in warm indices and negative in cold
ones, become more pronounced in the 1990s and particularly since the beginning of the 21st
century. Further research should focus on the assessment of the observed trends impacts on natural
and socio-economic systems
