When it comes to tapering your training down to competition or race/ match time, you've got to consider a few factors. Do not blow yourself out in the week leading up to competition, too many athletes believe that maximal training is what is needed in order to prepare the body for an event. This may be the case in the months leading up to competition in order to induce supercompensation (adaptation) and change, but the closer one gets, the more deliberate and careful the training should be. So if you know that you are due to compete in the heat in the next few weeks or months, then consider the following information proposed by triathloncompetitor.com which states...Submaximal exercise is enough to stimulate heat adaptations. So in other words, exercising at or around 50-80% ish is adequate to induce adaptation to heat during exercise. Researchers suggest that there is no need to perform key interval sessions or massive race distances/ times in order to acclimatise to heat. Light training in warm temperatures is often enough to get you ready, without burning you out completely (in both senses of the word).
Triathloncompetitor.com, (2014). How to train and race in the heat. Retrieved 24th July, 2014, from http://triathlon.competitor.com/2014/07/training/train-race-heat_102768