Ancient Douglas-fir (Pseudotsuga menziesii) trees from two forests in the Sierra Madre Occidental of Durango, Mexico, have been used to develop regionally-averaged tree-ring chronologies of earlywood (EW) and latewood (LW) width that are both over 500 years long. These partial ring chronologies have distinctive seasonal climate signals. The EW width chronology is significantly correlated with precipitation during the cool season, while the LW width chronology is correlated with early summer precipitation. We have used the EW chronology to develop a reconstruction of winter (Nov-Mar) precipitation that explains 53% of the variance of the instrumental winter precipitation data for Durango. We also used the LW chronology to reconstruct June rainfall, explaining 46% of the variance in the instrumental data. Both reconstructions extend from A.D. 1481-1993, and were verified against independent precipitation data for Durango during the 20th century. The winter precipitation reconstruction is significantly correlated with indices of ENSO, and the June rainfall reconstruction is correlated with early summer rainfall over a broad region in northwestern Mexico that is influenced by the Mexican Monsoon. Both reconstructions exhibit statistically significant spectral peaks in the ENSO frequency band, and reveal a drought of epic proportions in the late 16th century.