Radiocarbon dates on 16 pine stumps and trunks revealed the position of the alpine pine-forest limit for the biostratigraphic (i.e. pollen)-defined Atlantic period (8.2 to 5.0 ka BP) in the coastal mountains of south-west Norway. Based on the present topographic mean summer temperature gradients (mean temperature from June to September), and the difference in elevation between the alpine pine-forest limits of the present and the Atlantic periods, mean summer temperature differences between these periods in the forest limit zone are calculated as 0.7°C to the west and 1.0°C in the inner valley districts to the east of the watershed. On the eastern side the mean summer temperature difference becomes greater towards lower altitudes. The alpine pine-forest limits of both the present and the Atlantic periods are characterized by a marked west-to-east inclination. This indicates pronounced westerly winds during the Atlantic period, similar to those today, characterized by more cloudy weather, higher precipitation and less sunshine to the west than to the east of the watershed.