How much should a golfer drink on a humid August afternoon compared with a 40°F morning in November? The answer depends on the weather, and the colder round has a risk of its own, because thirst drops sharply in the cold while the body still loses water.

The Walking Load of 18 Holes

Golf is lower in intensity than most sports, and a walking round still adds up to a long stretch of moderate exercise. In a 2026 study of competitive golf, 16 low-handicap male golfers played competitive rounds on a championship course of 6,587 meters at 19°C, walking with a caddie in one round and riding a cart in the other. Walking took 17,007 steps and 880 kilocalories of activity energy, compared with 6,274 steps and 456 kilocalories in the cart, and core temperature was higher when walking at the 6th, 12th, and 18th holes.

Carry distance and clubhead speed were the same in both rounds. The difference showed up in heart rate, which rose across the walking round and fell across the riding round, and in perceived exertion, which was higher after walking.

A Walking Pace in Mild Weather

A 2023 review of nutrition in elite golf cited American College of Sports Medicine figures showing that walking at 5 to 6 km/h produces a sweat rate of about 400 ml an hour, a pace close to the demands of a round. Over a round of 4.5 hours in mild weather, that adds up to roughly 1.8 liters. The same review recommended that golfers start their round fully hydrated and keep fluid losses to no more than 1% of body weight, since losses of 1% to 2% have been shown to impair sport-specific cognitive performance. It also put the energy cost of a competitive round at about 700 kcal, mostly from carbohydrate, and suggested drinks containing electrolytes and carbohydrate during play.

Heat and humidity push the sweat rate higher, and the review noted that much of the research on golf and hydration comes from the UK and Ireland, where conditions are cooler than in the southern United States or Asia.

Heat and Humidity in Late Summer

The hottest stretch of the professional calendar falls in August, when the FedEx Cup playoffs move through Memphis, St. Louis, and Atlanta. Lucas Glover’s trainer said his plan in Memphis and Atlanta was a bottle of water with electrolytes every 2 holes, along with a snack. The heat is now affecting the schedule itself. Golf Channel reported in August 2026 that Memphis and Atlanta have been offered calendar changes for 2028, with Greensboro already expected to move to the spring.

During the 2023 playoffs, a memo to players described extra steps to keep players and caddies hydrated, including coolers with water and electrolyte drinks on every hole and shade tents with misting fans. At East Lake, the PGA Tour’s heat measures also included cooling devices for the hands on every third hole.

Recreational golfers rarely have a cooler on every tee. Players who buy hydration drinks for summer rounds can use the same structure as Glover’s plan, with one bottle every 2 holes and water from the course in between, and carbohydrate from a snack at the turn.

Dehydration and Scoring

Two studies have measured the effect on scores and shots. A 2017 study of 430 university and club athletes from a range of sports found a high prevalence of dehydration before and after training and competition. Among its golfers, players who started a competitive 18-hole round dehydrated took 79.5 strokes on average, against 75.7 for players who started hydrated. More than 40% of the golfers were dehydrated before play, and 60% afterward. In a separate 2012 study, mild dehydration reduced the distance of 9-iron shots from 128.6 meters to 114.6 meters and nearly doubled the inaccuracy, from 4.1 meters off target to 7.9 meters.

The 9-iron is a short, lofted club, so the effect on longer clubs may be larger. A gap of 3.8 strokes is the difference between a round in the mid-70s and one near 80.

Cold Mornings and Muted Thirst

Researchers at the University of New Hampshire had men walk for 60 minutes at a moderate pace in T-shirts and shorts at 4°C or 27°C in 2004, some of them already dehydrated, and a second phase with 9 men standing and then walking on a treadmill in the same 2 temperatures looked for the cause. Cold exposure reduced thirst by up to 40%, at rest and during the walk, and the effect held when the men were dehydrated. In the dehydrated trials, the hormone that signals the kidneys to retain water was also lower in the cold, even though the blood was more concentrated. The researchers linked the drop to narrowing blood vessels in the skin, which move blood toward the core and signal to the body that fluid levels are adequate.

A golfer in layers on a November morning still sweats on the walk between shots, though less than in summer, and is less likely to feel the need to drink. Robert Kenefick, who led the research, has said that people feel less thirsty in the cold and drink less as a result, and that fluid deficits of 3% to 8% of body mass have been reported in people working in cold environments. The fluid plan for a cold round is smaller, and it still has to be followed by the clock, since thirst gives a weaker signal.

Golf Carts and Fluid Needs

The 2026 study was commissioned by The R&A and the European Tour Performance Institute to test if carts give a competitive advantage, and it found none in swing or ball speed over a single round. The golfers in that study spent about half the activity energy in the cart that they spent walking, and their core temperature stayed lower. A cart rider in mild weather needs less fluid than a walker. On a hot day, riding lowers core temperature without removing the 4 or more hours spent outdoors in the heat. Post-round ratings of exertion in the study were 41 out of 100 after walking and 25 after riding, and ratings of physical demand on a standard workload questionnaire were also higher after walking.

Range Session at TPC Southwind

In August 2026, the heat index at the FedEx St. Jude Championship reached 109°F on Sunday. On the shade-sparse range at TPC Southwind that week, Golf Channel watched Justin Thomas stop between sentences to wipe sweat from his face, then ask his caddie, Matt Minister, for a cold towel. Keith Mitchell’s caddie, Brad Schneider, followed Minister to the cooler labeled for cooling towels, the 10th person to make that trip in 5 minutes, and both players finished their practice flushed red from the extreme heat, 2 Southerners who had grown up playing in it.