Phenological phases of plants are a bioindicator of climate change, it is accompanied by frequent weather extremes. Weather lores as a result of observing natural events in the past arose in a period of stable climate. Weather lores are currently evidence of climate change. The thesis verified the validity of weather lore and climate change on woody plants using phenological stages of flowering and leafing. Selected woody species: Crataegus laevigata (Poir) DC, Prunus spinosa L., Quercus petraea Liebl., Tilia cordata Mill. We verified wheather lores at an altitude range 111 – 855 m asl. and two time periods 1988 – 2003 and 2004 – 2019. A shift in trend of the onset of phases was found in a later period. There was a statistically significant shift of 11 – 16 days in the second period. The trend of phase delays was confirmed with increasing altitude. The validity of selected phenological weather lore was verified in regions of Slovakia. Weather lore "On Jakub and Filip date, every linden tree is green." was evaluated as valid with the highest incidence at altitude interval 240 – 475 m asl. Weather lore "On icy saints frosts burn all flowers." was confirmed as valid, but only at certain altitudes. Validity has not been confirmed for oak. The relationship between frost days (at a height of 2 m) and onset of the beginning of flowering is the statistically significant at most altitudes levels. The relationship is statistically significant only for Crataegus laevigata (Poir) DC at an height of 0.05 m. The results in the second part of the thesis evaluate course of vegetative and generative phases of 9 woody plants in two locations of the southern part of Kremnické vrchy Mts.. We evaluated the course of phenological phases in relation to extreme weather (frost, ice, summer and tropical days). There was a very strong correlation between frost and ice days and onset of phenophases (butonization and flowering) in most woody plants. A very strong correlation between summer and tropical days and the onset of yellowing and leaf fall was observed in most woody plats. Statistical significance has not been demonstrated. Different slope and exposure influenced the different onset of phenological phases of woody plants. The southern sunny slope caused earlier onset in the Boky location. The validity of the selected weather lores was not confirmed in the monitoring locations, but several temperature extremes were recorded. Climate change is causing earlier onset of spring phenophases and spring weather lores are becoming invalid but frost damage of flowers may be more frequent in various regions of Slovakia.