Climate graph of Tokyo
This graph shows that Tokyo has a has the highest temperature in August and has the highest amount of rainfall in June. This is very good for Tim Cahill as the soccer season in Japan starts in February and finishes June which means he would miss out on all the hot conditions which is very dangerous in sport because you have a more likely chance to get dehydrated. Also there is not much rain at all which makes it much better for playing soccer instead of playing it from July to December with more rain and hotter conditions.