if(
 $text =~ 
  m{ 
     (         #open capturing parenthesis
         \d+   #numbers before the period
         \.    #literal period
         \d+   #numbers after period
     )         #closing capturing parenthesis
     \s*       #optional spaces
     °     #degree symbol
     F         #literal letter F
  }xms){
     my $temp = $1;   # '$1' is what was found in capturing ()
     if($temp > 75){
         #code to send message
     }
}else{
    #code to deal with not finding temperature data.
}