In the 2010 world cup, south africa hosted. however, hot weather problems did not stop Spain from becoming champions.
referring to the world cup in Qatar.
According to several news sources that I read, in November, the temperature there is estimated to only reach 24 degrees Celsius. Even so, Qatar continues to innovate by installing air conditioning in every stadium to make it more friendly for players and spectators. as a result, the conditions in the stadium will certainly feel cool.
In an interview with FIFA, Dr Saud Abdulaziz Abdul Ghani, professor of mechanical engineering at Qatar University said "we not only cool the air, but also clean it".
So, it seems that weather or hot climate factors will not have a significant impact on the performance of all contestants who will compete later.
Climate and hot weather I think not problem for European and American countries have hot weather in their state, learned from many time World Cup edition from South Africa on 2010 and South Korean on 2002 keep have bigger chance for European and American country become the champion. Actually I don't see serious problem about hot weather in Qatar because World Cup edition this time begin at middle competition.
I worry with players not have enough time for recovery because few weeks only time preparing after several league around the world postponed preparing for World Cup, usually all Word Cup edition held after league ended and player have many time for recovery and rest time, but FIFA World Cup Qatar different after allowing begin at the middle league competition held.