Ambient temperature of objects not affected by environment

Certain objects within the ice biome are not affected by the temperature of the environment.

Checking the 'ambient temperature' shows several oddities: a ladder is exceptionally warm, random crops of sleet wheat are warmer than others although they're directly adjacent, and bottled water retains its warmth indefinitely.

The sleet wheat is especially problematic because the warm temperature stifles their growth, but I don't understand how they won't cool to match the ambient temperature.