Heat Pace Adjustment
Heat raises your heart rate and slows your pace. Enter your normal pace and the temperature & humidity to get a realistic adjusted pace.
Finish-time difference by distance Same effort — extra time from heat
| Distance | Cool day | Adjusted | Difference |
|---|---|---|---|
| 5K | — | — | — |
| 10K | — | — | — |
| Half | — | — | — |
| Full | — | — | — |
How it's calculated · sources
Heat pace loss is interpolated from the temperature-vs-slowdown tables widely used by coaches and research. Roughly no loss at or below 15°C (60°F), accelerating as it gets hotter.
- 20°C ≈ 2–3% slower
- 25°C ≈ ~5%
- 30°C ≈ 9–11%
- 35°C ≈ 14%+
Humidity adds a small amount above 60% (reduced sweat evaporation). The most accurate metric is actually dew point; this approximates it with temp + humidity.
Adjusted pace = normal pace × (1 + slowdown%). Finish time = adjusted pace × distance. On a hot race day, aim for finishing & condition, not a PB.
When it's hot, timing beats pace
Check the current temperature, air quality, and today's best running windows on the running-info page, and head out when it's coolest.
