The temperatures in Switzerland primarily depend on the altitude. In the northern lowlands, the average temperature in January is approximately 1°C and in July approximately 17°C. The corresponding average temperatures in the southern lowlands are 2-3° higher. At altitudes of approximately 1500 m a.s.l., the average temperature in January is about -5°C and in July about 11°C. Considering those locations in Switzerland where a series of observational data is available, Locarno-Monti in southern Switzerland is on average the warmest place with an annual mean temperature of 11.5°C. The coldest place, on the other hand, is the Jungfraujoch, located at 3580 m a.s.l., with an annual mean temperature of -7.5°C. The highest temperature that has ever been recorded in Switzerland, namely +41.5°C, was observed on 11 August 2003 in Grono in Southern Switzerland; the lowest temperature, -41.8°C, was measured on 12 January 1987 in La Brévine in the Jura Mountains.