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IRONMAN 70.3 CHATTANOOGA

Race-specific weather data and nutrition strategy for IRONMAN 70.3 CHATTANOOGA in Chattanooga, TN, US.

TriathlonHalf Ironman (70.3 mi)Registration Open
LocationChattanooga, TN, US
Date
May 17, 2026
RegisterBuild Your Fueling PlanOfficial website
Race Location35.05°, -85.31°
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Race-Day Conditions

Moderate Heat Risk
Temperature
81°F

75–84°F range

Humidity
79%

60–86% range

5-year average via Open-Meteo. 80% of race days fall within the range shown. Updated Mar 30, 2026.

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Moderate heat risk

Temperatures may reach 84°F. Plan for 10-15% higher sweat rates than cool conditions. Ensure adequate sodium intake (600-900 mg/hr) and consider pre-cooling strategies.

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High humidity conditions

Humidity averaging 79% combined with warm temperatures impairs sweat evaporation. Your body works harder to cool itself. Reduce intensity expectations and increase fluid intake.

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Segment transitions matter

Fueling needs differ across swim, bike, and run. The bike is your best opportunity for calorie intake — aim to consume 60-80% of total nutrition on the bike. Reduce volume entering T2 to avoid GI distress on the run.

Sample Ironman 70.3 Nutrition Plan

Based on a 155 lb triathlete finishing in ~6 hours. Your plan will differ based on body weight, experience, and conditions.

HourCarbsFluidSodiumExample
Swim + T125g9oz200mgGel in transition
Bike 175g26oz600mgDrink mix + gel
Bike 275g26oz600mgDrink mix + chews
Run 160g18oz500mg2 gels + water
Run 255g15oz400mgGel + cola
Total290g94oz2300mg

These are general estimates. Get your personalized plan for this race →

What to Expect at IRONMAN 70.3 CHATTANOOGA

IRONMAN 70.3 CHATTANOOGA is a Half Ironman (70.3 mi) ironman 70.3 held in Chattanooga, TN, US. Based on 5 years of historical weather data, athletes can expect median race-day temperatures around 81°F.

Temperatures at IRONMAN 70.3 CHATTANOOGA typically range from 75°F to 84°F. The upper end of that range crosses into moderate heat risk. While not extreme, sweat rates will be elevated and athletes who under-fuel on sodium or fluids may feel it in the later miles. A dialed-in hydration plan makes a real difference here. Humidity is also a factor here, with levels reaching 86% on warmer days. High humidity impairs sweat evaporation — your body's primary cooling mechanism — so perceived effort rises even when temperatures look manageable on paper.

A 70.3 sits in a nutritional sweet spot: long enough that fueling matters, but short enough that gut fatigue rarely becomes the limiter. Front-load calories on the bike and shift to a lighter fueling approach on the run. Most athletes target 60–80g of carbs per hour on the bike and scale back slightly for the half marathon.

We do our best to keep race details accurate and up to date, but things can change and occasionally we simply get something wrong.

Always check the official website for the most complete and current information.

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Fueling and hydration suggestions are based on published sports science research including ACSM position stands, ISSN guidelines, and peer-reviewed work by Jeukendrup, Sawka, and others. This is not medical or dietary advice — individual needs vary. Always test your nutrition strategy in training before race day.

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Frequently Asked Questions

What should I eat during the race?
Your nutrition plan depends on your body weight, experience level, and race-day conditions. Use our free calculator to get a personalized, hour-by-hour fueling plan with specific carb, fluid, and sodium targets for this Ironman 70.3.
What is the typical race-day weather?
Based on 5 years of historical data, race-day temperatures at Chattanooga, TN typically range from 75°F to 84°F (median 81°F). Humidity ranges from 60% to 86%.
How much water should I drink?
Fluid needs vary based on your sweat rate, body weight, and race-day temperature. A typical range is 400-800 mL per hour, but hotter conditions at Chattanooga, TN may require more. Our calculator provides personalized fluid targets adjusted for the expected weather.
How many calories do I need?
Rather than replacing all calories burned, focus on carbohydrate intake — the primary fuel for endurance performance. Target 30-50% of caloric expenditure through carbs. Our calculator computes the exact hourly targets based on your Ironman 70.3 pace and body weight.
When should I start fueling?
Begin fueling within the first 30-45 minutes. Start at about 70% of your target intake and ramp up to full by hour 2. This gives your gut time to adjust. Starting too late makes it nearly impossible to catch up on carbs and fluids.
Source: runsignup_playtriView sourceVerified: Mar 30, 2026Confidence: 85%