[paul.fr]

in the cold weather no matter how little i drink, it seems to go straight through me -with interest- and in no time i need to visit the little boys room.

what is it about cold weather and the need to wee more often?

[another_someone]

Three things that I would speculate upon:

1) reduced perspiration.
2) increased metabolic rate creating more waste product in order to generate more heat.
3) increased blood thickening in order to decrease freezing point, thus requiring the expulsion of more water to thicken the blood.

[Bored chemist]

I think the blood vessels near the skin shrink down in cold weather to reduce heat loss. There's less spacce in them for the blood and the easiest way to make room is to lose the water.

[ROBERT]

Why does cold weather cause frequency
of micturition in some elderly people?
Dr D KOHN and Dr EDITH FLATAU (Department
of Internal Medicine B, Central Emek
Hospital, Afula, Israel) write: Concerning the
question, "Why does cold weather cause
frequency of micturition in some elderly
people?" and your answer (12 July, p 120),
may we add another cause? Most old people
have rigid drinking habits and in cold weather
they excrete more water as their loss through
the skin and breathing diminishes.
Dr P E JACKSON (Stamford and Rutland
Hospital, Stamford, Lincs PE9 IUA) writes:
With reference to the question, "Why does
cold weather cause frequency of micturition in
some elderly people ?" (12 July, p 120), may
I make this observation ? Surely cold weather
causes polyuria and thus increased frequency
of micturition in everyone because we lose less
fluid through sweating.

http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1714278&blobtype=pdf