Africa
In December, it's winter in the Northern Hemisphere, so the heat is found only at southern latitudes.
Where to go: Benin, Ghana (east coast), Djibouti, Guinea, Guinea-Bissau, Kenya, Togo
Asia
The winter monsoon brings rainfall on the exposed slopes; for the rest at tropical latitudes the sunshine prevails. Sometimes, some late cyclones may reach the Philippines and Southeast Asia, especially in the first half of the month.
Where to go: Burma, India (west), Malaysia (Langkawi), Oman (south), Thailand (Pattaya, Phuket), Yemen
North and Central America
It's winter, and sometimes cool air masses can move southwards, down to the Tropic and beyond. In order to play on the safe side, it's better to go down in latitude.
Where to go: El Salvador, Guatemala (Pacific coast), Honduras (Pacific Coast), Mexico (Acapulco), Nicaragua (Pacific coast)
Caribbean Sea
It's the first month of winter, which is typically a good season in the Caribbean. However, some islands, the central and southern ones which receive more directly the north-east trade winds, are still quite rainy, and this also happens on the northern slopes of the northern islands. On the northernmost islands, there can be windy and cloudy days when
El Norte blows from the United States.
Where to go: Southern Bahamas (Inagua and Great Inagua), Dominican Republic (south coast), Venezuela (Maracaibo and islands), Colombia (Caribbean Sea), Puerto Rico (west coast), Jamaica, Anguilla, Antigua and Barbuda, Saint Kitts and Nevis, Saint Martin/Sint Maarten
South America
In the Southern Hemisphere it's summer, so heat and rain typically dominate at tropical latitudes, while at temperate latitudes (Argentina, Chile), the sea is a bit cold.
Where to go: Brazil (Fortaleza, Natal, Recife, Salvador)
Oceania
It's summer in the Southern Hemisphere, so the weather is hot and muggy, with heavy rains and the passage of tropical cyclones. In the Northern Hemisphere, some tropical cyclones can still form, at least in the first part of the month.