Sri Lanka lies on the Indian tectonic plate. It is in the Indian Ocean southwest of the Bay of Bengal, between latitudes 5° and 10°N, and longitudes 79° and 82°E. Sri Lanka is separated from the Indian subcontinent by the Gulf of Mannar and Palk Strait. The island consists mostly of flat to rolling coastal plains, with mountains rising only in the south-central part. The highest point is Pidurutalagala, reaching 2,524 metres (8,281 ft) above sea level. The climate is tropical and warm. Temperatures range from 17 °C (62.6 °F) in the central highlands, where frost may occur for several days in the winter, to a maximum of 33 °C (91.4 °F) in other low-altitude areas. Average yearly temperatures range from 28 °C (82.4 °F) to nearly 31 °C (87.8 °F). Day and night temperatures may vary by 14 °C (25.2 °F) to 18 °C (32.4 °F). The culture of Sri Lanka dates back over 2500 years.