Changes in temperature and precipitation affect tree growth. Height-diameter (h-d) models that include stand characteristics and climatic factors effectively predict tree height. We assessed 3,425 pine trees in Zambia (P. merkusii and P. michoacana) to (i) test the effectiveness of the existing general h-d model on these species; (ii) develop mixed-effect h-d allometric models that provide the best fit; and (iii) assess the effect of stand characteristics and climate on the predictive ability of the h-d models. The existing h-d model for pine significantly (p < 0.001) over-estimated height for P. merkusii (i.e., 20.5 m vs. 19.2 m) and P. michoacana (i.e., 22.2 m vs. 20.4 m). After incorporating random effects, the newly developed h-d models based on the mixed-effect modeling framework exhibited a high precision and accuracy in estimating height from diameter for P. merkusii and P. michoacana. A single and species-specific h-d models developed in the present study are recommended for inventory applications in Zambia. The temperature, dominant height, and basal area in large trees modulate the height to diameter relationship in P. merkusii and P. michoacana. This finding implies that the increasing temperature and decreasing precipitation beyond the optimum for these species will implicitly reduce tree growth and increase the rotation age.