Cuba, officially the Republic of Cuba, is an archipelago of islands located in the northern Caribbean Sea at the confluence with the Gulf of Mexico and the Atlantic Ocean. Cuba, the main island, consists mostly of flat to rolling plains apart from the Sierra Maestra mountains in the southeast, whose highest point is Pico Turquino (1,974 m/6,476 ft). The climate in Cuba is tropical and moderated by northeasterly trade winds that blow year-round. In general, there is a drier season from November to April, and a rainier season from May to October. The average temperature is 70°F in January and 80°F in July. Much of Cuban culture revolves around music and food; Cuban music and dance is the most commonly known expression of culture. The primary musical style is Son, which has been the basis of other musical styles such as salsa, rumba and mambo and an upbeat derivation of the rumba, the cha cha. Cuban cuisine is a fusion of Spanish and Caribbean cuisines. The official language of Cuba is Spanish and the vast majority of Cubans speak a local version known as Cuban Spanish, a dialect of Caribbean Spanish. Cuba has a dual currency system that may cause some confusion for tourists. Local wages and prices are set in Cuban pesos (CUP), while the tourist economy operates with Convertible pesos (CUC). Goods and services not oriented towards foreigners are usually paid in CUP. 'Luxury' goods and services, including most imported goods and anything intended for consumption by foreigners, are generally paid for in CUC. Currently, many state shops accept either currency. The conversion rate for Cuban convertible pesos may be considerably higher than local pesos.