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Safety 6 min read

Hydration for Babies and Toddlers in Summer Heat

By TinyPlate Team

A young toddler in pink-striped pajamas reaches up from a couch toward a red sippy cup held by an adult's hand.

Key Takeaways

  • Babies under 6 months should not be given water. Breast milk or formula provides all the hydration they need.
  • Babies 6 to 12 months can have small sips of water with meals (up to 4 to 8 ounces a day per AAP guidance), but breast milk or formula remains the primary source.
  • Toddlers 12 to 24 months can drink water freely, with most of their fluid still coming from milk and food.
  • Babies and toddlers lose fluid faster than adults in hot weather. Watch for fewer wet diapers, dry lips, and unusual lethargy.
  • Skip juice, sports drinks, sweet tea, and soda. Plain water and milk are the right answer.

Baby Hydration in Summer: Why It Matters

In a heat wave, dehydration risk is real for everyone, but babies and young children are more vulnerable than adults. Their body surface area is larger relative to their volume, so they lose fluid more quickly through sweat and breathing. They cannot communicate thirst well. And their thermoregulation systems are still maturing.

This is straightforward to manage with a few age-specific rules. Most parents already know the basics. The places people get tripped up are: when to start offering water, how much is too much, and what to do if signs of dehydration appear.

This post walks through the AAP and CDC guidance for baby hydration in summer by age.

Under 6 Months: Breast Milk or Formula Only

The AAP is clear: babies under 6 months should not be given water. Breast milk and formula are 87 to 90 percent water by composition, and they provide all the hydration a young baby needs. Offering plain water to a baby under 6 months can:

  • Displace breast milk or formula and reduce calorie intake.
  • Cause water intoxication (a rare but serious condition where electrolytes are diluted to dangerous levels).
  • Make breastfeeding less effective by reducing the baby's appetite for the next feeding.

What to do in summer: Offer breast milk or formula more frequently. Babies nurse more in heat, which is normal and exactly what they should do. Formula-fed babies can be offered the next bottle a little earlier than the usual schedule. Do not water down formula. Use the manufacturer's instructions for mixing.

6 to 12 Months: Small Sips of Water With Meals

Once your baby starts solids around 6 months, the AAP allows small amounts of water with meals: 4 to 8 ounces total per day across a few short servings. The goal is to:

  • Practice drinking from a cup (open cup or straw cup, not a bottle).
  • Aid digestion of solids.
  • Stay hydrated in warm weather.

Breast milk or formula is still the primary fluid source. Water supplements, not replaces.

What to do in summer: Continue with the regular breast milk or formula schedule. Offer a small open cup or straw cup of water with each solids meal. On very hot days (above 85 degrees Fahrenheit), an extra ounce or two of water mid-afternoon is fine.

Open cup or straw cup, not a bottle: Water in a bottle increases the risk of tooth decay and slows the natural progression away from bottle dependence. The AAP recommends introducing an open cup or straw cup around 6 months.

12 to 24 Months: Water Available Freely

After the first birthday, the AAP and the CDC both recommend that water and plain whole-fat cow's milk be the primary drinks for toddlers. Water is available throughout the day. The exact amount varies, but typical guidance is:

  • About 4 cups (32 ounces) of total fluid per day, including water and milk.
  • Roughly 16 ounces of whole milk per day. Past this, calcium can start to interfere with iron absorption.
  • The rest as water.

What to do in summer: Keep a small cup of water within reach at home. Pack a water bottle for outings. Offer water before, during, and after outdoor activity.

A toddler who refuses water sometimes responds to:

  • A novel cup (the same water in a new straw cup is sometimes more interesting).
  • Adding a slice of cucumber or a few berries to the water for flavor.
  • Offering water alongside a salty or savory food.

Signs of Dehydration to Watch For

Both the AAP and CDC publish the same signs. Mild dehydration:

  • Fewer wet diapers (less than 6 in 24 hours for a baby; less than 4 in 24 hours for a toddler).
  • Darker, more concentrated urine.
  • Dry lips.
  • Unusual fussiness or low energy.
  • A slightly sunken soft spot (fontanelle) in babies under 18 months.

Moderate to severe dehydration (call your pediatrician or seek urgent care):

  • No wet diaper for 8 hours or more.
  • Sunken eyes.
  • Significantly sunken fontanelle in young babies.
  • Lethargy, difficulty waking.
  • Crying with no tears.
  • Cold, mottled skin.
  • Rapid breathing or pulse.

Severe dehydration is a medical emergency. Call 911 or go to an emergency room.

Hydrating Foods Help Too

In summer, food can carry significant water:

  • Watermelon is 92 percent water and one of the easiest summer fruits for babies. (See the summer fruits guide for stage-by-stage cuts.)
  • Cucumber (peeled, seeded, cut into small soft pieces) for older babies.
  • Strawberries are about 91 percent water.
  • Cantaloupe and honeydew are over 90 percent water.
  • Yogurt and milk-based foods carry significant water.

A baby who eats a few servings of high-water-content fruit on a hot day is meaningfully better hydrated than one who eats dry crackers.

What to Skip

A few drinks that get marketed at parents or that adults reach for, but should not be in regular rotation for babies and toddlers:

Juice (even 100 percent fruit juice): The AAP recommends no juice for babies under 12 months. For toddlers 1 to 3 years, no more than 4 ounces per day of 100 percent juice. Most parents find it easier to skip juice entirely. Whole fruit delivers the same nutrients with fiber and without concentrated sugar.

Sports drinks (Gatorade, Powerade, etc.): Designed for athletes losing electrolytes through prolonged exercise. Not appropriate for babies or toddlers. Too much sugar and sodium.

Sweet tea, lemonade, soda: Empty calories, high sugar, no nutritional value for young children.

Coconut water: Sometimes marketed as a natural electrolyte drink. The AAP does not recommend it as a primary fluid for babies and toddlers due to its sodium content and the lack of established safety data in young children.

Plant-based milks (almond, oat, soy): Not nutritionally equivalent to cow's milk for toddlers. Some are appropriate in specific cases (a confirmed cow's milk allergy or family preference), but only after a conversation with your pediatrician about how to make up the nutritional difference.

Pedialyte and similar oral rehydration solutions: Only when recommended by your pediatrician (typically for diarrhea or vomiting). Not for routine hot-weather hydration.

A Note on Outdoor Activity

Some practical tips for summer outings:

  • Schedule outdoor time for early morning or late afternoon when temperatures are lower.
  • Babies under 6 months should not be in direct sun. Use shade, hats, lightweight long-sleeved clothing.
  • Babies over 6 months can use sunscreen (SPF 30 or higher, water-resistant). Apply 15 minutes before going outside and reapply every 2 hours.
  • Take a water break every 20 to 30 minutes for toddlers active outdoors.
  • Watch for signs of overheating: flushed face, fast breathing, irritability, decreased activity. Move to shade or air conditioning immediately.

What TinyPlate Does Differently

Hydration is one factor among many in feeding a small child. The Weekly Meal Plan inside TinyPlate naturally weights high-water-content fruits (watermelon, cucumber, berries) into the summer recipe rotation, so your baby gets fluid through food without you tracking it explicitly. The Safety Search flags age-appropriate drinks for any child's stage: "is coconut water OK for a 14-month-old," with the answer in seconds.

Download TinyPlate free on the App Store.

Sources

  • American Academy of Pediatrics. "Choosing Healthy Beverages for Kids." HealthyChildren.org.
  • American Academy of Pediatrics. "Hydration in Kids." HealthyChildren.org.
  • Centers for Disease Control and Prevention. "Hydration." CDC Healthy Schools.
  • U.S. Department of Agriculture. "Dietary Guidelines for Americans, Birth to 24 Months." USDA, 2020 to 2025.
  • American Academy of Pediatrics. "Fruit Juice in Infants, Children, and Adolescents." Pediatrics, 2017.