At Punta Arenas, in the extreme south, the mean temperature is 6 °C (43 °F) and the average extremes are 24.5 and −2 °C (76.1 and 28.4 °F). The prevailing winds are westerly, and the westward slope has a much heavier precipitation than the eastern in a rainshadow effect;[31][1] the western islands close to Torres del Paine receive an annual precipitation of 4,000 to 7,000 mm, whilst the eastern hills are less than 800 mm and the plains may be as low as 200 mm annual precipitation.[17]