Races›Ultra 100 Mile

High Lonesome 100

Race-specific weather data and nutrition strategy for High Lonesome 100 in Nathrop, CO, US.

RunningUltra 100 MileRegistration Open
LocationNathrop, CO, US
Date
July 17, 2026
Register on RunSignUpBuild Your Fueling PlanOfficial website
Race Location38.75°, -106.08°
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Race-Day Conditions

High Heat Risk
Temperature
83°F

77–88°F range

Humidity
54%

39–62% range

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

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High heat risk

Race-day temperatures can reach 88°F. Expect 15-25% higher sweat rates. Increase sodium to 800-1200 mg/hr and plan for more frequent fluid intake. Pre-cool with ice and cold fluids.

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Gut fatigue management

For races lasting 6+ hours, gut absorption efficiency decreases over time. Plan to reduce carb intake by 10-15% after hour 6 and shift toward easily digestible sources like gels and simple sugars.

Sample Ultra 100 Mile Nutrition Plan

Based on a 155 lb runner finishing in ~24 hours. Your plan will differ based on body weight, experience, and conditions.

HourCarbsFluidSodiumExample
Hours 1–6360g120oz3000mgGels, chews, drink mix
Hours 7–12300g115oz3000mgReal food rotation + gels
Hours 13–18240g101oz2400mgBroth, potatoes, cola, gels
Hours 19–24200g86oz2000mgWhatever works + caffeine
Total1100g422oz10400mg

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

What to Expect at High Lonesome 100

High Lonesome 100 is a Ultra 100 Mile ultra 100 mile held in Nathrop, CO, US. Based on 5 years of historical weather data, athletes can expect median race-day temperatures around 83°F.

Temperatures at High Lonesome 100 typically range from 77°F to 88°F. This puts the race squarely in high heat risk territory. Sweat rates can increase 15–25% in these conditions, meaning both fluid and sodium demands rise significantly. Athletes should plan for increased hydration, consider pre-cooling strategies, and expect pace adjustments — even well-trained runners slow 1–3% per 10°F above 60°F.

Ultra-distance racing demands a flexible nutrition strategy. Gut absorption efficiency declines over many hours, so plan for variety — alternating between gels, chews, real food, and liquids helps prevent flavor fatigue and GI rebellion. Many ultra runners find that what works at hour 3 is intolerable by hour 10. Build your plan with options, not rigid prescriptions.

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 Ultra 100 Mile.
What is the typical race-day weather?
Based on 5 years of historical data, race-day temperatures at Nathrop, CO typically range from 77°F to 88°F (median 83°F). Humidity ranges from 39% to 62%.
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 Nathrop, CO 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 Ultra 100 Mile 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_apiView sourceVerified: Mar 30, 2026Confidence: 95%