And if you prefer one-liners
curl "http://www.mywebsite.com/update_temp.php?rig=1`DISPLAY=:0;aticonfig --adapter=all --odgt | awk 'BEGIN {counter=1} /Temperature/ {printf "&temp"counter++"="$5}'`"
At first I thought maybe sed could do this, but after 30min of trying sed, and spamming the google search, I gave up and gave awk a shot and was surprised at how easy and powerful the syntax was.