South America's large size and highly varied geography mean the weather differs greatly from one place to another. That said, there are a few common trends. Tropical conditions prevail over more than half of the continent. Much of South America experiences two distinct seasons, wet and dry. Elevation, oceans and wind have a large impact on regional weather. A rise in Pacific ocean temperatures, known as El Niño, affects the climate of South America every two to five years causing heavy rainfall in the arid coastal regions of Ecuador and Peru. The climate in the Amazon river basin is tropical rainforest. It's hot, wet and sticky throughout the year. The Andes mountains are cooler than neighboring low-lying areas. The desert regions of Chile are the driest part of South America. The highest recorded temperatures occur in the Gran Chaco region of Argentina. In Patagonia, winters are long and cold and the wind always blows.

Some places in South America have earned a reputation as dangerous destinations and the continent, as a whole, has a long list of infectious diseases, yet most travelers will be perfectly safe by taking sensible precautions and traveler's diarrhea is the health problem most travelers encounter. BEFORE BOOKING: Research the health and safety risks in the country or countries you plan to visit. Check government sources for travel advisories, travel health notices, and recommended vaccinations. Consult your health care provider or travel medicine clinic 2 to 3 months in advance of travel as some immunizations require a series of injections. The World Health Organization (WHO) advises that all travelers, independent of their travel destination, be up to date with routine vaccinations against measles, rubella, mumps, diphtheria, tetanus, pertussis (whooping cough) and poliomyelitis. Additional vaccinations, such as rabies, may be recommended by your doctor. There is no vaccine for malaria but prophylactic treatment is recommended for travel to risk areas. PRIOR TO DEPARTURE: Review your medical coverage to ensure it applies abroad and covers emergencies, for example a trip to a foreign hospital or an evacuation. If not, supplemental travel health insurance should be given serious consideration. Pack a first aid kit. Check expiration dates and ask your doctor or pharmacist for advice on items to include as well as tips for keeping the contents of your kit effective and safe to use. Organize your family's essential medical history in a single document and keep it with your travel papers. Make two copies of your passport, medical history, travel documents and credit cards. Bring one copy with you but keep it in a separate place from the originals. ON THE ROAD: Take sensible precautions. - Don't wear jewelry and expensive watches. Stow cameras after use. Keep a firm grip on daypacks and handbags. Safeguard valuables including passports and money. Avoid isolated or deserted areas. Keep an eye, if not a hand, on the kids. Beware of hustlers, touts and con men. - Be careful about what you eat and drink. - Wash your hands before eating. Avoid raw foods. Peel uncooked fruits and vegetables. Drink bottled water only. Avoid unpasteurized dairy products, including milk, cheese and ice cream. - Safeguard against the southern sun. - Wear sunglasses and a hat with a brim. Apply high factor sunscreen to all exposed areas. - Traveling to a malaria area? No drug is 100% effective in preventing malaria thus it's important to avoid mosquito bites. Here are three tips: 1) use insect repellent with DEET. 2) Wear trousers and long-sleeved shirts after dark. 3) Sleep under a treated mosquito net or in a screened or air conditioned room.