Surfing Session Day: Fuel, Hydration, Sun and Cold Water

This article contains affiliate links: if you buy through them we may earn a commission, at no extra cost to you. Learn more.

The alarm goes at 5:15. You check the buoy readings, grab the board and a banana, and you’re in the water as the sky turns pink. Three hours later you paddle in, starving, salty and sunburned on the backs of your knees. That’s a great day of surfing, and a day you can plan better. Whether it’s a dawn patrol before work, a grom’s first contest, a college club event, a long day on a surf trip or a heat on the pro tour, this is the Session Day guide: what to eat and drink, how to handle sun and heat, and how to stay safe in cold water.

General information, not medical advice. If you have a heart condition, diabetes or take medicines that affect fluids or heat, ask your doctor how to plan long sessions. Prices change often; the prices below are what we saw at the maker or a major retailer in October 2026. Back to the surfing hub.

Before you paddle out

• Check the ocean, not just the waves. Look at the surf forecast, tide, wind and the National Weather Service rip current risk. NWS notes rip currents often form on calm, sunny days. Surf near a lifeguard when you can, and tell someone where you’re going.
• Eat something. The American College of Sports Medicine and the sports dietitians’ groups suggest a carbohydrate-based meal or snack 1 to 4 hours before exercise, familiar and not too heavy in fat or fiber. At dawn that can be just a banana and toast or a bowl of oats; before a midday session, a proper meal.
• Drink. The same guidance suggests about 5 to 10 mL of fluid per kilogram of body weight in the 2 to 4 hours before, aiming for pale yellow urine. For a 70 kg (154 lb) surfer that’s roughly 350 to 700 mL, about 1.5 to 3 cups.
• Sunscreen on dry skin about 15 minutes before you go in (more below), and warm up on the sand.

Hydration: you’re thirsty in the ocean

Surrounded by water, it’s easy to forget you’re sweating. A 2026 scoping review of fluid balance in surfers pulled together seven studies: on average surfers lost about 1.3% of body mass and 0.57 liters of fluid an hour. Surfers in wetsuits lost more than those without (1.05% vs 0.59% of body mass), and elite surfers in wetsuits were reported losing 1.68 liters an hour, a 3.9% drop in body mass, enough to likely hurt performance. The authors note the research is limited and that surfers’ losses vary with conditions and what they wear.

The National Athletic Trainers’ Association (NATA) suggests keeping fluid losses to no more than about 2% of body weight, and drinking to thirst when you don’t know your sweat rate. For surfers that means: drink before you go, leave a bottle on the beach, and come in for a drink and a snack on sessions longer than about 90 minutes or in hot, tropical water. Want to know your own number? Weigh yourself before and after a session (dry, in the same clothes). A sports drink or electrolyte mix such as Skratch Labs Hydration or Nuun Sport tablets adds sodium you lose in sweat; check labels and our best electrolyte powders guide. Don’t overdrink, either: drinking far more than you sweat can be dangerous.

Fueling long sessions and contest days

A 2-hour session is mostly paddling and waiting, at a moderate heart rate with bursts of sprinting (GPS studies average about 128 beats a minute). Two or three hours of that burns through breakfast. Practical ideas:

• Between sessions: a sandwich, rice and beans, fruit, yogurt or a smoothie; then rest in the shade before going back out.
• Contest days: heats are short but the day is long. Eat small, familiar snacks every couple of hours (bananas, pretzels, a granola bar, a PB&J), keep a bottle in the shade, and check the heat draw so you eat 1 to 2 hours before your heat. Try nothing new on contest day.
• After: carbohydrate and protein together, and more fluid. Details are on our surf recovery page and the nutrition page.

Teens: energy drinks don’t belong in the cooler. The American Academy of Pediatrics says energy drinks have no place in the diets of children and adolescents.

Sun: the longest exposure in sport

Few athletes spend as many hours in direct sun as surfers, and the water reflects it back. The American Academy of Dermatology recommends a broad-spectrum, water-resistant sunscreen of SPF 30 or higher, about 1 ounce (a shot glass) for the body, applied about 15 minutes before going out and reapplied every two hours and after swimming or sweating. Water resistance runs out: Blue Lizard’s Sport Mineral SPF 50 is labeled for 80 minutes, so reapply when you come in for a drink. A UPF 50+ long-sleeve rash guard like the O’Neill Basic Skins covers the back and shoulders, a surf cap helps on long tropical days, and polarized sunglasses on the beach protect against “surfer’s eye” (see surfing injuries).

Heat on tropical trips

Warm water doesn’t cool you much, and a long session at midday in the tropics plus the walk back across hot sand adds up. NATA recommends 7 to 14 days to get used to the heat. Know the warning signs of heat exhaustion: heavy sweating, weakness, dizziness, headache, nausea. Get out of the sun, cool down and drink. Confusion, collapse or strange behavior can mean heat stroke, an emergency: call 911 and cool the person right away. Surf early and late, and take the middle of the day off.

Cold water: dress for the water, not the air

The National Weather Service defines cold water as 70°F (21°C) or below, which covers much of the US coast for much of the year. The first danger is cold shock: a gasp and fast breathing that peaks in the first 30 seconds or so and settles over the first few minutes. NWS warns that within about 10 minutes you can lose muscle control, and prolonged exposure leads to hypothermia. Its advice fits surfers exactly: wear cold-water protection for the water temperature, not the air temperature.

• Wetsuit: choose thickness from the maker’s water-temperature chart; add booties, gloves and a hood as it gets colder. A hood and earplugs also protect against surfer’s ear.
• Enter calmly and let your breathing settle before you duck-dive into cold water.
• Know when to go in. The CDC lists the warning signs of hypothermia: shivering, exhaustion, confusion, fumbling hands, memory loss, slurred speech and drowsiness. Fumbling hands that can’t work the leash or a buddy who stops making sense means it’s time to get out.
• Warm up after: the CDC’s first steps for hypothermia are getting to a warm place, removing wet clothes and warming the core with blankets; give warm, non-alcoholic drinks if the person is alert, and get emergency care if body temperature is below 95°F. A changing poncho, warm clothes and a thermos in the car make the change much faster.

Lightning and storms

Sitting in the ocean on a board during a thunderstorm is a bad place to be. NATA’s lightning guidance: “When thunder roars, go indoors.” If you can hear thunder, lightning is close enough to be a hazard, and no place outside is safe. Get out of the water, get into a building or a hard-topped car, and wait 30 minutes after the last thunder before paddling back out.

After the session, the job switches to recovery: food, fluids, a rinse and sleep. That’s on our recovery page. Team-sport athletes can compare with soccer game day.

Session Day: FAQs

What should I eat before a dawn patrol?

Something small and easy on the stomach, mostly carbohydrate: a banana, toast with honey, a granola bar or a bowl of oats, plus a glass of water. If you’re out for more than a couple of hours, have a bigger breakfast when you get in.

Do surfers get dehydrated?

Yes. A 2026 review found surfers lose on average about 0.57 liters an hour, more in wetsuits, and elite surfers in wetsuits were reported losing up to 1.68 liters an hour. Drink before you go and come in for fluids on long sessions.

How often should I reapply sunscreen when surfing?

The AAD says every two hours and after swimming or sweating. Water resistance is time-limited (check the label; Blue Lizard Sport’s says 80 minutes), so reapply whenever you come in. A rash guard means less skin to cover.

What water temperature is “cold” for surfing?

The National Weather Service calls water of 70°F (21°C) or below cold water. Cold shock and loss of muscle control are real risks, so wear a wetsuit rated for the water temperature and add a hood, gloves and booties as it gets colder.

Should I get out of the water for lightning?

Yes. NATA says if you can hear thunder, you’re close enough to be struck. Paddle in, shelter in a building or hard-topped car, and wait 30 minutes after the last thunder.