As cold blooded they prefer the heat, they can deal with cold weather but if its too cold -50 they will refuse to go further. If forced they will attack, if still forced they will end up going into a deep sleep, and will most likely not wake up from such a deep slumber . True dragons do not suffer from this as their magic help protect them.

due to this wyvern immunity to cold they do not fall prey to the standard problem to cold but they do not like it when it is this cold because it makes them feel numb and lesser they do lose movement in temp less then -50 at 5 ft per -5 below this temp due to this its harder to hunt and generally avoid such areas unless great need for it arises 

Bite. Melee Weapon Attack: +7 to hit, reach 10 ft., one creature. Hit: 11 (2d6 + 4) piercing damage.

Claws. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) slashing damage.

Stinger. Melee Weapon Attack: +7 to hit, reach 10 ft., one creature. Hit: 11 (2d6 + 4) piercing damage. The target must make a DC 15 Constitution saving throw, taking 24 (7d6) poison damage on a failed save, or half as much damage on a successful one.

Breath Weapons (Recharge 5–6). The dragon uses one of the following breath weapons.

Cold Breath. The dragon exhales an icy blast in a 30-foot cone. Each creature in that area must make a DC 17 Constitution saving throw, taking 56 (8d12) cold damage on a failed save, or half as much damage on a successful one.

Paralyzing Breath. The dragon exhales paralyzing gas in a 30-foot cone. Each creature in that area must succeed on a DC 14 Constitution saving throw or be paralyzed for 1 minute. A creature can repeat the saving throw at the start of each of its turns, ending the effect on itself on a success.