Ok so I am using this mod for the first time, and I feel the biome temperature is kind of weird.
I am using Insulated armor, and I am currently in the nether, not using the hellfire lamp, but for some reason is VERY cold there.

Also, when I am in the overworld, in a forest biome, around 70 in the Y level, during the day, for some reason the temperature drops very fast. Even with the insulated armor.
And lighting a fire or being next to a campfire does nothing to that.

I just feel we could get a clearer mod explanation.
I read the wiki but I am still confused.

I've heard reports of the world being extremely cold from other people as well. Trust me, it's not supposed to be like that (the Nether should be about 130 °F / 54 °C). I'm looking into it right now.

I've found the problem. It will be fixed in 2.1.9.2 later today