If Chicago race day runs warm, slow your pace from the start and drink early and often. Drop any personal-record goal and let the official alert level guide your effort. The Event Alert System is the race's color-coded safety signal. The Bank of America Chicago Marathon describes it in medical volunteer policies as Low/green to Moderate/yellow to High/red to Extreme/black, based mainly on weather.
Medical information disclaimer: This article is for general educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a physician or other qualified health professional about symptoms, medications, tests, or treatment decisions.
Table of Contents
- What will the alert color mean for you?
- How much should you slow down?
- Where do you get fluids on the Chicago course?
- How do you drink enough without overdoing it?
- When should you pause or seek care?
What will the alert color mean for you?
Green means lower risk, while yellow calls for caution and strategy change. Red signals high risk and black signals extreme risk, including possible stoppage.
Chicago staff have raised the level to yellow before a warm start. Reporting on that 2015 race says the medical team used yellow to tell all 26.2-mile runners to decrease pace and change strategy.
How much should you slow down?
Start slower than planned and hold back through the first half. Effort will feel harder than the watch suggests, so run by feel and keep surges out.
Loyola Medicine reports sports-medicine physician Dr. Winger advises warm-day runners to expect slower times and abandon record goals. Warm days reward finishing strong, not chasing a breakthrough.
Where do you get fluids on the Chicago course?
Coach Parry's race guide reports what you will find at the water tables as 20 aid stations about every 1-2 miles. Each offers lemon-lime Gatorade Endurance first, then water, plus toilets and medical tents nearby.
Canadian Running Magazine reports Chicago added four filtered-water refill stations in 2025. They sit just before aid stations at miles 5.7, 10.1, 15.7 and 20.3, while disposable cups remain available.
- Carry a flask or cup if you want refills without slowing much.
- Drink at the first stations, even when you feel cool.
- Use both Gatorade Endurance and water across the race.
How do you drink enough without overdoing it?
The Road Runners Club of America advises pre-drinking water 10-15 minutes before running. It also advises drinking every 20-30 minutes during the run in heat.
Drink to thirst during exercise and avoid passing about 800 mL per hour. Guidance summarized from the American College of Sports Medicine in exercise and fluid replacement warns that overdrinking can cause dilutional hyponatremia.
- Pre-drink before the start corrals.
- Take small sips at regular time intervals.
- Stop increasing intake once thirst eases.
When should you pause or seek care?
Heat risk rises fast during prolonged effort like a marathon. The National Weather Service rates 80-90°F heat index as Caution with possible fatigue and 90-103°F as Extreme Caution with possible cramps, exhaustion or stroke.
The Road Runners Club of America advises avoiding running when heat exceeds about 98.6°F with 70-80% humidity. Slow down at cramps, dizziness, nausea, confusion or goosebumps in heat, then use the nearest aid-station medical tent.