Temperatures before and after the update are much different. Yellowstone from terralith for example, a presumably rather warm biome is now at 16 degrees as opposed to 53 degrees (which still feels rather low).
Before update:

After update:

Hot shrubland keeps fluctuating even while I'm standing still. Anywhere from 39-72.

Just moving around from block to block makes the temperature fluctuate wildly.

I would advise resetting your world.toml config file. I'm not experiencing either of these things with default configs.