Lowest Average Body Temperature

I'm writing in an urban supernatural setting where the antagonist has thermal sensing magic. I plan for my protag to use some sorta body temperature lowering spell, and perhaps somehow raise the the average temperature in the room that he's in. In either case, the effects will only be temporary.

So my question to you, how low can the average human's body temperature go? And for how long can a human maintain this bare minimum without dying?

Hypothermia sets in when your core temperature goes below 95-96 degrees. Without outside influences a human body will never go below that on its own.

Once you go below 95 symptoms are very apparent. People will become confused and uncoordinated, and won't be able to pass basic sobriety tests like walking on a straight line. Unless they warm back up ASAP they're at risk of some severe health issues. Below 90 means loss of consciousness, and then death.

Hypothermia is pretty serious business, even mild hypothermia can lead to cardiac arrest if you're not careful. If you were cooling yourself on purpose you probably wouldn't want to go below 95 degrees.

I see, thanks.

Perhaps the magic merely makes it appear that his body temperature was lowered? Like a shielding spell?

Heating up the room would still work.

Also, if the enemy is using some kind of thermal vision a very cold obstacle could block it. For example, if the protagonist can manipulate temperature with magic maybe he could make a cloak or cape very cold without it freezing him when he puts it on. It would basically be a thermal invisibility cloak. You can buy thermal camo clothing as well, which uses bands or blocks of metallic fabrics to break up the heat signature of your body.

They did something like that in Predator 2. The team attempting to capture him wore suits that masked their body heat — so the Pred simply switched his mask to see Ultraviolet light instead.

edited 29th May '18 2:20:38 AM by pwiegle