At present, the temperate forest ecosystems are endangered by both abiotic and biotic factors. The effects of abiotic components, e.g., meteorological variables are constantly studied. However, we still don´t know the mechanisms affecting the phenology of plants in detail. Two meteorological variables (air temperature and cumulative precipitation) during the period 1995–2020 were analysed to find the factor which has more significant effect on onset of the full-flowering (FF) phenophase. The set of nine forest herbs, representing different phenological groups from the viewpoint of flowering, was examined (early spring - Petasites albus and Pulmonaria officinalis, mid-spring - Carex pilosa and Dentaria bulbifera, late spring - Fragaria vesca and Galium odoratum, early-summer - Veronica officinalis, mid-summer - Mycelis muralis and late summer - Campanula trachelium). In addition, temperature sum requirements as well as the temporal trends for onset of FF were studied. The research was done at Ecological Experimental Station in Kremnické vrchy Mts. (Central Slovakia) at altitude of 500 m a.s.l. Our results showed that the air temperature correlated more significantly with the dating of onset of FF (r > 0.6, P < 0.001), compared to the precipitation. Temporal trends in the onset of FF over the last 26 years confirmed the shifts to the earlier dates for most species (excepting early-spring Petasites albus), however the trends were statistically significant (P < 0.05) for five examined species (Carex pilosa, Dentaria bulbifera, Fragaria vesca, Veronica officinalis and Mycelis muralis).