When searching for cheap flights to Brazil it is most important to know when to go! Brazil is an enormous country with fifteen major cities each with their own unique climate and the price of airline tickets to Brazil varies dramatically from one city to the next. Brazil is located in the southern hemisphere therefore the seasons in Brazil are the reverse of those experienced in Europe. Salvador de Bahia has a tropical climate, and Manaos, the capital of the Amazon, an equatorial one, both of which don't change throughout the year.
To find a well-priced flight to Brazil you could opt to fly to Rio de Janeiro from August to November. Take care though, it is winter in Rio in August, so don't bank on being able to swim in the sea! The most expensive time to fly to Brazil is between May and July. Funnily enough it is during the Carnival in February when there are the most cheap flight deals to Brazil! The weather in Brazil in December and January, during the summer, can be stiflingly hot with highs of 40°C! Flights from London to Rio de Janeiro for these months cost on average £1000.
Iguaçu with its world-famous falls are found in the south of the country, on the border with Argentina. Here it is cold in August (almost 0°C!) and warm in December and January (30°C). The cheapest flights to Iguaçu are in October; however even then tickets to Brazil are relatively high. The Brazilian company TAM, Air France and TAP Portugal via Lisbon are the main airline companies offering flights to Brazil, but for the cheapest flights to Brazil you should choose a flight from the Spanish company, Air Europa, via Madrid.