Total annual rainfall in the city averages although in the Southern Suburbs, close to the mountains, rainfall is significantly higher and averages closer to . Summer, which lasts from December to March, is warm and dry with an average maximum of and minimum of . The region can get uncomfortably hot when the Berg Wind, meaning "mountain wind", blows from the Karoo interior. Spring and summer generally feature a strong wind from the south-east, known locally as the south- or the Cape Doctor, so called because it blows air pollution away. This wind is caused by a persistent high-pressure system over the South Atlantic to the west of Cape Town, known as the South Atlantic High, which shifts latitude seasonally, following the sun, and influencing the strength of the fronts and their northward reach. Cape Town receives about 3,100 hours of sunshine per year.