Weather is the most underestimated variable in race performance. Here's what you need to know.
The Ideal Conditions
Research shows optimal marathon performance occurs at:
WBGT: The Key Metric
Wet Bulb Globe Temperature combines temperature, humidity, wind, and sun exposure into a single number. It's what your body actually feels.
| WBGT | Risk Level | Expected Impact |
|---|---|---|
| Under 65°F | Low | Ideal conditions |
| 65-73°F | Moderate | 1-3% pace slowdown |
| 73-82°F | High | 3-6% pace slowdown |
| Over 82°F | Extreme | 6%+ slowdown, DNF risk |
How Heat Slows You Down
When it's hot, your body diverts blood from muscles to skin for cooling. This means:
Adjusting Your Plan
For every 10°F above 55°F:
Cold Weather Tips
Running in cold weather has challenges too:
Using FuelFox's Weather Analysis
FuelFox provides 5-year historical weather averages for your race date and location, including: