A snowy minecraft:mountains biome in 1.17.1 becomes a rainy minecraft:windswept_hills in 1.18.1. Replacing snow with rain can be a problem since it kills all snowmen and it prevents the natural re-generation of snow layers. Temperature change also affects the ability to freeze water to get ice blocks.

Expected result: A snowy biome in 1.17.1 should remain snowy in 1.18.1

Repro steps:

In Minecraft 1.17.1:

• Create a new world with seed: 1851255519
• Teleport to a snowy biome: /tp -8620 115 9733
  • In that case biome is minecraft:mountains
• Change weather to rain: /weather rain
• RESULT: Snow is falling
• Close Minecraft

Open same world in Minecraft 1.18.1:

• RESULT: Biome has changed to minecraft:windswept_hills (as expected)
• UNEXPECTED RESULT: Snow is replaced by rain. The biome is no longer a snowy biome.