This post is the second part of the argument that can be found here. The argument of that post was that the effects of climate have to severely affect the character's statistical ability to function, otherwise they will simply ignore (or fail to account for) the rule. It further argued that weather is indifferent and affects all player characters without exception (no saving throws). This post continues on these principles.
Proposed Rules for Cooler Temperatures
Unfortunately, we cannot treat cooler temperatures in the same manner as warmer, simply by removing points from character abilities. While few especially enjoy a cold day, we can mitigate a cooler climate with appropriate clothing - gloves, hats, jackets, cloaks, coats, sweaters, mufflers, fur trimming and so on all serve to make the intolerable tolerable. If it then starts to become warm, we can simply strip off this clothing as necessary, especially if we layer what we're wearing so that mid-day and midnight can be managed easily while adventuring.
However, there are consequences of working (or participating in combat) while wearing protective clothing - just as there are consequences to stopping work after heating up. Even though it is cold, the body begins to sweat - and the moreso if the body is wearing a heavy coat that is not removed as we heat up. Even if we do remove that coat, once we begin to cool down after exertion, we can experience a terrific shock if the weather is very cold to start.
Consider - the characters get into a combat when the weather is 'brisk.' As you can see to the right, this is around 45 F/7 C. They're wearing the logical clothes for this sort of weather, a jacket and cap (at least this is logical in Canada!) - which has the effect of making the climate comfortable (I'd consider it cool rather than pleasant).
As they get into the battle, they begin to heat up. After 8 rounds, the effective ambient temperature becomes 'cool' while the temperature in the jacket is 'pleasant.' The combat advances to 16 rounds and the character continues to heat up. Now the ambient temperature is 'pleasant' but with a jacket on it is 'warm.' At once, the player loses a point from their stats across the board.
So the player tears off their jacket, cooling off immediately and extending the period when they can fight without penalty until the 32nd round.
But the battle ends on round 25. The character pants and begins to cool down. In 27 rounds (in my world that is only 6 minutes), the character cools down again to the point where they can put on the jacket without losing ability points (assuming we're using the cool-down rate I used in the previous post).
Only something very different has happened here. When we sweat in a 'balmy' temperature, this is a good and comfortable thing. We receive mostly positive effects from heavy sweating. But when we sweat profusely in a climate that is 'cool' or 'brisk,' we risk getting a reaction from cooling down quickly due our core body temperature being challenged. That means the cooling down rate of 3 rounds to 1 round of work doesn't work - because in fact in a cold climate you can cool down too fast. Suddenly you are colder than you mean to be. Instead of the ambient temperature feeling like it cools down to 'brisk,' it plummets right to 'chilly' or even 'frosty.'
Now you're in trouble. You're covered with sweat and even if you pull on the jacket, you are still wet. Being wet + cold + exhausted is a great way to bring on rapid hypothermia. You can die from that.
So what we need are some pretty vicious rules that account for hypothermia - things that insist that the characters get a fire going before they dilly-dally around with things like gathering up treasure. Even chasing an enemy through a wood for ten or twelve rounds can get you into trouble.
Granted, in the example above, the chance for hypothermia ought to be pretty low. I suggest that if the experienced heat climbed two grades during the battle (as I described in this case), then after the battle it ought to drop two grades below whatever the actual ambient temperature is. In the above example, I described that as being 'brisk.' So the ambient temperature experienced by someone after a 25 round battle ought to be 'frosty.'
Once the temperature drops to 'chilly,' the core body temperature for the individual is threatened enough that we can reimpose a drop in stats (35 F/2 C is the point when hypothermia can begin to affect the body's core). This equals -1 across the board at 'chilly' (which includes the point where water freezes), -2 for 'frosty,' -3 for 'icy' and so on. Thus, our characters in the above example would need to make a constitution check against hypothermia at -2 (effective temperature 'frosty') to their constitution. Failure equals hypothermia.
The effects of hypothermia are easy enough (see link). The main problem is that the body begins to lose heat rapidly - so that if something isn't done, the individual will die. But there is lots that can be done - provided you are not running from a pack of ice wolves - such as starting a fire, wrapping the character in DRY clothing, heating potatoes that can be held in the hands, sharing body heat or building a shelter that will collect lost body heat and perhaps additional heat from a candle or lantern.
If none of these things are done - or if the character suffering from the hypothermia has gone off alone and can't be found - then the character will absolutely die.
Even if a check against hypothermia is made, the situation hasn't changed. If the characters don't get dry and warmer very soon, they will need to make another check and another, perhaps every 2-5 minutes (certainly no longer). It can take a long time to die from hypothermia but getting it can come on pretty rapidly if you're not prepared.
That means EXTRA clothes when marching about the wild, kept dry; and picking when you want to get into combat, since you don't want to get caught out in the wild having to be on the run while soaking wet. Once we've established rules for losing stats after combat in cold climes, accounting for these things becomes the difference between life and a TPK.
Have a look at this comment of William Jones' and my answer. In the case of the character from Asyut (and living there), that cold shock can kick in when the temperature is merely cool (night in the desert). Thus the rule helps explain the effects on those shivering in the middle of the night in the Sahara.
There's something to be considered, too, for the fellow from Haerpin. That fellow may be used to a 'brisk' climate . . . but body temperature is the same for everyone. Thus, while he considered the yearly temperature at home to be pleasant, that is pleasant only so long as he is wearing protective clothing. Once he is naked and wet in a brisk temperature, his core temperature is as shit as anyone's.
This is all a bit complicated - moreso than the last post. Still, it would really give people pause. It's bloody cold outside - do you really want to get into a combat?
There may not be an option, there - but I'm going to leave that for a third post. There was a lot more in the above than I expected.