The Bug:

Temperatures don't properly get converted when upgrading to 1.18. This can cause snow golem to die.

Steps to Reproduce:

• Create a world in 1.17.1 with the seed: 3289848721474072111
• Do /tp @s -17 ~ 563
• Leave and open the world in 1.18 pre-release 1
• Summon a snow golem at your position

Observed Behaviour:
The temperature changed and the golem died

Expected Behaviour:
The temperature wouldn't change