This question comes up on these forums periodically, and it is a common and not illogical question. However, the answer is definitively NO, the temperature of incubation does not affect the gender.
It has been said, and it may be the case, that males may survive harsher conditions and therefore temps that are wrong (high or low or too much fluctuation) may result in more males hatching. But it won't *change* the gender of the baby in the egg, only affect how many females die during incubation vs males dying during incubation. And it's not even clear whether that idea is even true.
Gender is determined while the egg is still inside the female, based on which genes she has passed on to her half of the embryo--like humans, but in reverse (i.e., it is the male's contribution that determines gender in humans).