Gather as much thermal energy as possible before you fight the worm. To get 
more thermal
energy, destroy the surrounding heat tankards and activate the outpost. If 
you need more
thermal energy, just kill the surrounding flying Akrid and their spawn 
points. Get a sled VS
and attach either a rocket launcher or gatling gun (recommended). Ride it 
just to the entrance
of the Snow Plain. If you ride it any further the worm will knock you off 
and destroy the VS.
Once you get off the sled VS, take off the weapon you brought with you. The 
gatling gun is
recommended because if you miss you can adjust your aim and keep shooting 
him unlike the
rocket launcher. Wait until he emerges from the snow and be ready for him to 
either growl or
charge at you. If he charges and hits you, you are dead. You can either roll 
to the left or right.
After the roll aim at his sides and you will see several weak points. Shoot 
at them until they
explode and reveal a reddish boil. Continue to do this until they are all 
gone then switch sides.
Once he is hurt enough he may start shooting flaming balls that explode from 
his backside. Be
ready to evade them. Once again you will see more weak points. Do the same 
thing as done
with his head side and he will eventually die. When he dies he will leave 
behind a large deposit
of thermal energy. The worm will re-appear no matter how many times you kill 
it.
Also the achievement for killing it will not appear until you complete the 
level.