The climatic, elevational and edaphic factors are the major abiotic determinants of survival and reproductive behavior of plant pathogenic nematodes and thus responsible for their occurrence, population levels and severity of symptom development. Present study attempted to determine relationship between rainfall, soil temperature and soil moisture on soil and root population densities of Pratylenchus loosi, the key nematode pest of tea in six different elevation regimes in Sri Lanka. Rainfall, soil temperature and soil moisture of six locations were recorded by standard methods over 18 months. P. loosi populations in soil and root samples obtained from the same locations were also monitored using standard methods. The fluctuating nematode population density was correlated with rainfall, soil temperature and soil moisture. There was a positive correlation of P. loosi population density with mean rainfall and negative correlation with soil temperature and soil moisture content in majority of the tested locations. Results also revealed an increase in mean soil temperature above the optimal range for development of P. loosi and a remarkable change in soil temperature range of 18-240C. However, there were exceptions in some locations indicating that factors other than temperature have influenced nematode population. Nevertheless, presence of P. loosi at increased soil temperature ranges beyond the acceptable range was evident in certain locations making disease expressions and damage to tea. Therefore, further investigations are warranted on the presence of new biotypes and the influence of other factors for development of P. loosi population in view of developing specific management strategies.