Sierra de Otontepec Ecological Reserve is an isolated mountain in the Coastal Plain of Gulf of Mexico with great scientific importance. However, it lacks climatological information to support the studies of the ecosystems that have been carried out in recent years. Through GIS modelling its climatology was characterized, and climate variability scenarios were created for the period 1981-2010. From temperature and precipitation data recorded in situ, vertical gradients of both variables were obtained in relation to the orography of the zone. The records were correlated with data from nearby weather stations so that by using a DEM it was possible to obtain raster layers with a resolution of 15 m per pixel for temperature, in the summer and winter seasons; and for precipitation, in the rainy and dry seasons; the annual value was also calculated for both variables. The climatic variability detected in the zone indicates a gradual increase in air temperature over time and a spatial variation in the distribution of precipitation. The spatial resolution of the modelling is precisely adjusted to the relief of the mountain, allowing the flora and fauna elements found within each pixel to be analysed with a good level of detail. This work represents the most viable and effective alternative to estimate temperature and precipitation values in mountain systems lacking climatological stations; demonstrating that beyond providing climate information, which is increasingly necessary for ecosystems, it is possible to model their spatio-temporal dynamics to better understand the complex climate variability of our days.