Where are you from? We in Asia have no seasons so it really doesn't matter much if it's end or middle of the year, both times are when our own leagues don't play anyway.
I still don't get why it's a problem for most people, it's not like we are the ones playing football there, and most of the teams are on their off season anyway (except Europe but that's their problem lol).
Everyone will be playing under the same weather conditions. So it doesn't matter if it's summer or winter. Because the conditions are the same for everyone. It will also be nice to watch the struggles to be experienced in different weather conditions. If the players start camping two weeks before the tournament, they adapt to the weather conditions.