Adventuring characters will often travel to areas where they are exposed to extremes of temperature. These extreme temperatures can be as deadly as the most ferocious monster.

Heat

When operating in temperatures above 90 degrees Fahrenheit (32 degrees Celsius) a character must make a Save vs. Con (TN 20) every hour or receive a cumulative -1 modifier to all actions. If the temperature is above 100 degrees Fahrenheit (43 degrees Celsius), the Save must be made every 10 minutes.

The modifiers will remain until the character can cool off by locating shade, immersing himself in water, or waiting until night falls.

If the character is wearing heavy clothes or armor, increase the Save TN by 2 points per step (i.e. Soft Leather armor gives a Save vs. Con (TN 22), Reinforced Leather gives Save vs. Con (TN 24), etc.).

If the temperature is above 130 degrees Fahrenheit (54 degrees Celsius), the character will take 1d10 points of heat damage for every failed Save. If the character is wearing metal armor, change it to 2d10 hits of heat damage.

Cold

Hypothermia and freezing to death are two of the main hazards when dealing with extreme cold.

When operating in temperatures below 40 degrees Fahrenheit (4 degrees Celsius) a character must make a Save vs. Con (TN 20) every hour or receive a cumulative -1 modifier to all actions. If the temperature is below 0 degrees Fahrenheit (-18 degrees Celsius), the Save must be made every 10 minutes.

These modifiers can only be reduced by the character finding a place of warmth in which he can warm up. The modifiers will be reduced by -1 for every 10 minutes spent enjoying the warmth.

Should a character reach a modifier of -20, he will need to make another Save vs. Con (TN 25) or he will fall asleep and freeze to death in a number of hours equal to 1d10 plus his Constitution stat bonus.