Do You Need Less Water in Winter? Hydration in Winter for Athletes
Put a well-hydrated person in a cold room and their thirst drops by up to 40%. Put a dehydrated person in the same room and their thirst drops too (Kenefick et al., Med Sci Sports Exerc, 2004).
The short answer
Athletes need less water in winter than in summer, but not as much less as their thirst suggests. Cold blunts thirst, while sweat under layers and moisture lost through breathing in dry air keep losses going. Drink to thirst but check urine colour, and warm water counts just as much as cold.
Quick Overview
Hydration in winter for athletes: do you need less water?
Yes, in most cases, because you sweat less when the air is cool. A tempo run at 6°C (43°F) costs less fluid than the same run at 30°C (86°F). The trouble is the size of the drop. Winter losses fall less than most people assume, and intake usually falls further.
Which winter matters, too. The Mumbai Marathon runs in January in temperatures a Londoner would call summer, and November in Perth is the start of summer. This post is about cold conditions: single-digit Celsius mornings in Delhi's winter fog, a Sunday league match in Manchester in January, a day on skis in Colorado or the Alps. If your winter is warm, your summer habits still apply.
Why do you feel less thirsty in the cold?
Cold weather switches off part of your thirst signal. When your skin gets cold, the blood vessels near the surface narrow to hold heat in, and more blood sits in your core. Your body reads that extra central volume as a sign it's well filled. So thirst falls, and so does arginine vasopressin, the hormone that tells your kidneys to hold onto water. In cold-exposure trials, thirst dropped by up to 40% at rest and during moderate exercise, including when participants were already dehydrated (Kenefick et al., Med Sci Sports Exerc, 2004).
So "drink to thirst" still works as a starting point in winter, but thirst arrives later and quieter. That's why the urine check below sits alongside it.
Where does the water go in winter?
It leaves through three routes that are easy to miss: sweat under clothing, breathing, and extra urine.
Sweat under layers is the biggest. A thermal top and a jacket on a hard interval session will have you sweating within fifteen minutes, and because cold air dries the skin fast, you don't feel wet. Indoor sport is worse. A badminton or squash session in a heated hall can produce
sweat losses close to summer levels, with none of the summer cues to drink.
Breathing is the second. Cold air holds very little moisture, so your airways warm and humidify every breath, and that water leaves when you breathe out. The harder and longer you breathe, the more you lose, which adds up over a two-hour run or a day on skis.
The third is cold-induced diuresis. The same narrowing of skin blood vessels that blunts thirst also pushes your kidneys to produce more urine. If you've ever needed the toilet straight after a cold warm-up, that's why.
How much water should you drink in winter?
Start from a daily baseline and add your training losses on top. European reference values set total water intake at about 2.0 litres (roughly 3.5 pints) a day for women and 2.5 litres for men. That covers food and drink combined, with around 70–80% expected to come from drinks (EFSA, EFSA Journal, 2010). It's a floor for a sedentary day in a temperate climate, not a training-day target.
For the training part, use the scale. Weigh yourself before a session and again afterwards, in the same dry clothes or none, and allow for anything you drank. Each kilogram lost is roughly one litre of fluid. Do this test in winter conditions, because your summer number won't hold. Aim to keep losses during a session under about 2% of body weight, which for a 70kg (154lb) athlete is 1.4kg. Afterwards, replace about 1.5 litres for every kilogram lost. Spread it across the next few hours and meals rather than downing it in one go (Sawka et al., Med Sci Sports Exerc, 2007).
For most winter sessions under an hour, plain water is enough. Sodium becomes relevant on long sessions with heavy sweating, including long indoor sessions in heated halls (McCubbin, Performance Nutrition, 2025). The post on electrolytes and hydration covers this in more detail. The muscle cramps post explains why salt isn't the cramp fix it's sold as.
How can you tell if you're drinking enough?
Check your urine colour. Pale straw means you're fine; the colour of apple juice means drink more. Colour tracks urine concentration closely enough for field use, though not for lab precision (Armstrong et al., Int J Sport Nutr, 1994).
Three things throw it off. First-morning urine is always darker, so judge it later in the day. B-vitamin supplements turn urine bright yellow regardless of hydration. And a lot of water drunk quickly runs clear before your body has caught up. Pair colour with a morning weight check. A drop of more than a kilogram from your usual morning weight, with darker urine, usually means you're behind.
Does warm water hydrate as well as cold?
Yes. Water at 50°C (122°F) hydrates you as well as water at 5°C (41°F). What matters is the volume that actually goes down, and in winter people drink more of a warm drink than a cold one. An ice-cold bottle left in the car after training tends to come home untouched.
Chai, coffee, green tea, hot milk, soups, rasam and miso all count towards your fluid. A flask of something warm after a cold session does more for hydration than good intentions about the water bottle.
The Fueletics Perspective
In winter I'd rather athletes plan their fluid than wait for thirst to ask. Layers, heated gyms and long efforts in dry air keep the losses going while the signal goes quiet. The fix is small: one weigh-in test per season, a warm drink within reach after training, and a glance at urine colour in the afternoon.
Sweat rates differ widely between athletes doing the same session (Sawka et al., Med Sci Sports Exerc, 2007), which is why copying a teammate's bottle routine rarely works. If you want your own fluid and fuelling numbers set for your training and your climate, start with a Fueletics assessment. The weigh-in number you get in January is the one to plan your winter around.
FAQ
Do you need to drink water when running in the cold?
Yes. You still lose water through sweat under your layers and through breathing cold, dry air. For runs under an hour, drinking normally before and after is usually enough. For longer runs, carry water.
Can you get dehydrated in winter?
Yes. Cold blunts thirst by up to 40% and increases urine output, so it's easy to drink less than you lose without noticing.
Is it bad to drink cold water in winter?
No. Cold water hydrates just as well as warm. Warm drinks are simply easier to drink in cold weather.
How much water should an athlete drink per day in winter?
Start from about 2.0 litres a day for women and 2.5 litres for men from food and drink. Then add back what a pre- and post-session weigh-in shows you lose in training.
Research References
Kenefick RW, Hazzard MP, Mahood NV, Castellani JW. Thirst sensations and AVP responses at rest and during exercise-cold exposure. Med Sci Sports Exerc. 2004;36(9):1528–1534. doi:10.1249/01.MSS.0000139901.63911.75
Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. American College of Sports Medicine position stand: exercise and fluid replacement. Med Sci Sports Exerc. 2007;39(2):377–390. doi:10.1249/mss.0b013e31802ca597
Armstrong LE, Maresh CM, Castellani JW, et al. Urinary indices of hydration status. Int J Sport Nutr. 1994;4(3):265–279. doi:10.1123/ijsn.4.3.265
EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific Opinion on Dietary Reference Values for water. EFSA Journal. 2010;8(3):1459. doi:10.2903/j.efsa.2010.1459
McCubbin AJ. Sodium intake for athletes before, during and after exercise: review and recommendations. Performance Nutrition. 2025;1(1):11. doi:10.1186/s44410-025-00011-9
