In this article we review the main characteristics of the Patagonian climate, the spatial and temporal patterns of the most important climatic variables, and the influence of climate on ecosystem processes. The winter distribution of precipitation determines an asynchrony between the wet and the growing season in Patagonia. The amount of water that can be transferred from the wet season to the growing season depends mainly on the physical characteristics of the soil. In the semiarid steppe of Chubut, drainage accounted for 10% of annual precipitation. Winter distribution of precipitation determines also an asynchronic dynamics of evaporation and transpiration fluxes. The ENSO phenomenon have a significant impact on regional precipitation. In central-west Patagonia, spring precipitation (September to November) was lower than normal during La Niña events and greater than normal during El Niño events. From December to February the opposite pattern can be observed: higher than normal precipitation during La Niña events and lower than normal precipitation during El Niño events. The impact of this phenomenon on the seasonal temperature was not as clear as for precipitation. We did not detect any temporal trends in annual precipitation for the period 1961-1996. The phenology of carbon gains is quite homogeneous in Patagonia. Most of the region showed a peak of production in November, when, simultaneously, water availability and temperature are high. Toward the west, production peaked later (December). Deciduous forests showed the peak in January and February
