This is what I've come up with....
Starvation and Thirst
In normal climates, Medium-size characters need at least a gallon of fluids and about a pound of decent food per day to avoid starvation. (Small characters need half as much.) In very hot climates, characters need two or three times as much water to avoid dehydration.
A character can go without water for 1 day plus a number of hours equal to his Constitution score. After this time, the character must make a Constitution check each hour (DC 12) or sustain 1 point of temporary Constitution damage.
A character can go without food for 3 days, in growing discomfort. After this time, the character must make a Constitution check each day (DC 12) or sustain 1d2 points of temporary Constitution damage.
Characters who have taken temporary Constitution damage from lack of food or water are fatigued. Temporary Constitution damage from thirst or starvation cannot be recovered until the character gets food or water, as needed—not even magic that restores ability score damage heals this damage.
Cold Weather
Cold and exposure deal temporary Constitution damage to the victim. This temporary Constitution damage cannot be recovered until the character gets out of the cold and warms up again. Once a character’s Constitution score becomes three, he is rendered unconscious and continues to suffer damage until dead or no longer suffers from cold weather exposure.
An unprotected character in cold weather (below 40° F) must make a Fortitude saving throw each hour (DC 15) or sustain 1d2 points of temporary Constitution damage. A character who has the Survival skill may receive a bonus to this saving throw and may be able to apply this bonus to other characters as well.
In conditions of extreme cold or exposure (below 0° F), an unprotected character must make a Fortitude save once every 10 minutes (DC 15), taking 1d2 points of temporary Constitution damage on each failed save. A character who has the Survival skill may receive a bonus to this saving throw and may be able to apply this bonus to other characters as well. Characters wearing winter clothing only need check once per hour for cold and exposure damage.
A character who sustains any temporary Constitution damage from cold or exposure suffers from frostbite or hypothermia and is fatigued. These penalties end when the character recovers the temporary Constitution damage he or she took from the cold and exposure.
Thoughts?
Can somebody check 3.5 and see if this has changed?