Mongolia’s climate is described as extreme continental climate with short, warm summers and long, cold winters. The warm summer lasts from May to September with an average daily temperature of 20°C. During this short period of time Mongolia displays its beauty of nature and attracts many tourists. The country, known as “land of blue sky”, has about 250 cloudless days a year. Average temperatures over most of the country are below freezing from November through March and close to it in April and October. Winter days are mainly – 25 °C (-13 °F) but sometimes can drop to −35 °C (−34 °F) in most years. Summer days are around 20 °C, but extremes reach as high as 40 °C (104 °F) in the Great Gobi area and 33 °C (91.4 °F) in Ulaanbaatar. All rivers and freshwater lakes freeze over the winter which prodive great opportunity to develop winter tourism in the country.