Weather reports from the last weeks in Santa Fe with highs and lows
www.timeanddate.com
It was like 28-26 degrees when they were playing. Considering the team was in Brisbane for the SA game and that all Australian super teams have pre-season in summer, I don't think this tempreture had an impact on decision making.
As long as they were getting enough water and good glycogen replacements, they would have been fine.
If you're concerned about the decision making being made after 30+ minutes then your touching on a fitness issue rather than a tempreture issue. The less fatigue you have, the quicker and better snap decisions you're able to make.
Given the recent history by coaches like Chieka and Rennie coming out and saying our players aren't fit enough, it is probably the more logical reason.