Golf in the heat: the heat index, a drink on every tee and the signs that mean you stop

Most rounds in the heat are not lost on the first tee. They are lost somewhere around the 13th hole, when the legs go heavy, the putts come up short and every decision gets a little lazier. The front nine felt fine because the body was still running on the water and the breakfast it started with. The back nine is where the bill arrives. Here is how to plan a hot round so that the last six holes are played by the same golfer who teed off, with the federal heat guidance that sits behind each step.

Why the back nine is where heat costs you

A round of golf is a long, moderate effort: four to five hours on your feet, several miles of walking if you skip the cart, and short bursts of effort a few dozen times. That profile is exactly the one that lets dehydration creep up unnoticed. You never feel out of breath, so you never feel that anything is wrong.

What does change is small and cumulative. Fine motor control, the thing that sets the speed of a putt, slips first. Then patience goes: you take the driver on a hole that called for an iron, you skip the second look at a putt. By the time you notice that you are thirsty, you have usually been short of water for a while. The goal of everything below is to keep that slide from starting, not to recover from it once it has.

Read the heat index, not the thermometer

Ninety degrees in Phoenix and ninety degrees in Houston are not the same round. Humidity decides how well sweat cools you, and the National Weather Service folds it into the heat index, the temperature it “feels like.” The NWS uses four bands:

• Caution, 80 to 90°F: fatigue is possible with prolonged exposure and activity.
• Extreme caution, 90 to 103°F: heat cramps, heat exhaustion and heat stroke are possible.
• Danger, 103 to 124°F: cramps and heat exhaustion are likely, heat stroke is possible.
• Extreme danger, 125°F and above: heat stroke is highly likely.

One detail matters a great deal for golfers: those values are calculated for shade. The NWS notes that full sunshine can add up to 15°F to the heat index. A fairway at noon has no shade at all, so a forecast heat index of 92°F can play like the danger band. Check the hourly forecast, not the daily high, and look at the hour you expect to be on the 14th tee.

Choose the tee time before you choose the ball

The single most effective decision is made the evening before. In a hot spell, the first tee times of the day are the coolest hours you will get, and the course is usually quiet enough for a round of under four hours. A 6:30 a.m. start in late summer often finishes before the worst of the afternoon builds.

Twilight is the other option, and it is often cheaper, but be honest about it. The ground and the air have stored the whole day’s heat, and the humidity can be higher in the evening than at dawn. Twilight works when you can finish nine holes before dark and you have eaten properly during the day.

If you are stuck with a midday time, cut the round rather than push through it. Nine holes in the heat count for handicap purposes, and they are far better than eighteen played on empty for the last third.

Drink on a schedule, not on thirst

Thirst is a late signal. The approach that works, borrowed from workplace heat guidance, is to drink small amounts at fixed intervals. NIOSH, the federal agency that writes heat-stress advice for outdoor workers, recommends about one cup (8 ounces) of water every 15 to 20 minutes during moderate activity in the heat, which is roughly three quarters of a quart to a quart per hour.

On the course, that translates into something simple: a few mouthfuls on every tee box, whether or not you feel like it. Start before the round, with a glass of water at breakfast and another on the range.

Two limits matter just as much. First, more is not always better: NIOSH warns against drinking more than 48 ounces an hour, because too much plain water can dilute the salt in your blood. Second, plain water does not replace what you lose in sweat. On a long, hot round, alternate with an electrolyte drink or eat something salty at the turn. Pretzels and a sports drink do more for the back nine than a hot dog and a beer.

Eat small and often

A heavy meal before a hot round sends blood to the stomach that the rest of you would rather use for cooling. A light breakfast, then something small every four or five holes, keeps the energy level flat: a banana, a handful of nuts, half a sandwich. Many golfers notice that the 15th-hole slump looks a lot like low blood sugar, because partly it is.

Alcohol deserves a plain sentence: it does not help in the heat. If the group’s tradition is a beer at the turn, swap it for the 19th hole.

Dress for the sun, not for the photo

Light colors reflect sunlight, and loose, breathable fabric lets sweat evaporate. A dark polo that clings is the opposite of both. Beyond the shirt:

• Headwear. A wide-brimmed hat shades the ears and the back of the neck, which a cap leaves bare. If you prefer a cap, add sunscreen on the neck or a neck shade.
• Sunscreen. The American Academy of Dermatology recommends a broad-spectrum, water-resistant sunscreen with an SPF of 30 or higher, reapplied every two hours and after heavy sweating. A round lasts more than two hours: put a small tube in the bag and reapply at the turn.
• Grip. Carry two towels, one for the face and one kept dry for the grips, and a spare glove. A wet glove twists in the hand on the downswing.
• Cooling towel. A towel soaked in cold water from the cooler, worn on the neck between shots, is the cheapest air conditioning on the course.

Cart or walk?

Walking is good golf and good exercise, and nothing here is an argument against it in normal weather. In the danger band of the heat index, though, carrying a bag over four or five miles adds a real load. A push cart is the middle ground: you keep the rhythm of walking without the bag on your shoulder.

If you ride, use the cart for what it is good at. Park it in the shade while you play your shot when you can, keep the cooler on the seat rather than in the sun, and do not sit in a cart roof’s shade for five minutes and then sprint to the green. The cart cools you only if you use the time in it to drink.

Play the shot the heat gives you

Hot weather changes the golf course as well as the golfer, and adjusting your game is part of finishing well.

• The ball flies a little farther. Warm air is less dense, so carry distances grow slightly compared with a cool morning. Do not chase extra yards; just notice whether you are long and club down if you are.
• Fairways run, greens may not. In a hot spell, fairways often firm up and release the ball, while superintendents may raise mowing heights and water greens to keep the grass alive. Putt a few on the practice green before you assume they are fast.
• Afternoon wind. On many courses, the breeze builds as the ground heats up. Plan the back nine with lower, controlled shots in mind.
• Shorter thinking time. Make the decision in the shade of the tree by the tee, then step into the sun and swing. Standing over the ball longer only adds heat.

One rules point that often comes up: under Rule 10.2b(5) of the Rules of Golf, you may hold your own umbrella or wear protective clothing while you play, but you must not make a stroke while your caddie, a partner or an object deliberately placed gives you protection from the sun. Shade from a friend’s umbrella is fine between shots, not during the swing. The penalty is two strokes in stroke play, loss of the hole in match play.

Know the warning signs, and stop

The CDC separates two conditions that every golfer playing in the heat should recognize.

Heat exhaustion shows up as heavy sweating, cold, pale and clammy skin, a fast and weak pulse, nausea, muscle cramps, tiredness, dizziness or headache. The response is to stop playing, get to a cool place, loosen clothing, put cool wet cloths on the body and sip water. Get medical help if the person vomits or the symptoms get worse.

Heat stroke is an emergency. The signs are a body temperature of 103°F or higher, hot, red, dry or damp skin, a fast and strong pulse, headache, dizziness, nausea, confusion or loss of consciousness. Call 911, move the person to a cooler place, cool them with cool cloths, and do not give them anything to drink.

On a golf course, the hard part is the decision, not the first aid. Nobody wants to be the one who walks off on the 12th. Agree with your group on the first tee that anyone can stop without explanation, and that the others will drive them in. Tell the pro shop where you are if you need help: the staff know the fastest route for an ambulance to every hole, and you do not.

Where the heat lasts into the fall in the U.S.

Across most of the country, October brings the best golf weather of the year. In the desert Southwest and much of Texas and Florida, it does not, at least not yet. The National Weather Service’s normal high for Phoenix in October is about 90°F, so the opening weeks of the month still call for early tee times and a full cooler. Florida’s heat index stays high because of the humidity even when the thermometer looks reasonable.

Fall in the desert also brings overseeding. Many Arizona and Southern California courses close for a few weeks between late September and October to plant winter grass over the dormant summer turf, and the courses that stay open play cart-path only or on temporary greens. Check the course’s own site before you book a trip; a third-party listing may not show the closure.

For heat on the day, the National Weather Service issues heat advisories and extreme heat warnings by county, and its HeatRisk forecast rates each day’s risk on a color scale for the week ahead. Many courses in hot regions post their own policies: free water stations, cooler refills, earlier first tee times or reduced rates for nine holes in summer. Ask at the pro shop rather than assuming. Your state or regional golf association lists member courses and posts tournament heat policies when events are affected.

If you play in a club league or a local event, read the committee’s weather notice. Some events in hot states shorten the round or move the start time when the heat index crosses a set level. That is not the committee being cautious for its own sake; it is the same NWS chart doing its job.

The hot-round checklist

• The evening before: check the hourly heat index for your tee time and the three hours after it. Book the earliest time you can, or plan nine holes.
• Before you leave: freeze a bottle, fill another, pack electrolytes, two towels, a spare glove, sunscreen and a wide-brimmed hat.
• On the first tee: agree that anyone can stop without explanation. Note the pro shop’s phone number.
• Every tee box: a few mouthfuls of water, whether you feel thirsty or not.
• At the turn: sunscreen again, something salty, refill the bottles. Skip the beer.
• From the 13th: quicker decisions, lower shots if the wind picks up, and an honest check on how you feel.

A hot round played this way is not a heroic one. It is simply a round in which the 18th hole is played as well as the first, which, on a hot day, is already an achievement.

How this page was put together: the heat index bands come from the National Weather Service, the warning signs and first aid from the CDC, the hydration figures from NIOSH guidance for outdoor workers, the sunscreen advice from the American Academy of Dermatology, and the umbrella rule from Rule 10.2b(5) of the Rules of Golf, all read in October 2026. This page is general information, not medical advice: if you have a heart condition or take medication that affects how you handle heat, ask your doctor before playing in hot weather. Panxis Golf has no commercial relationship with any organization or product mentioned here.