@stuff = my($low_temp, $high_temp, $average_temp = split(/\s+/,$line); 
$stuff[0] is $low_temp. 
Do I need a #define LOW_TEMP 0\ /*low_temp var*/$stuff[LOW_TEMP]? NO! 
I just use the variable name that has just been declared: $low_temp.
Forget the idea of $stuff[0] or $stuff[LOW_TEMP].