Optimal temperature Optimal Running Temperature

Ambient temperature has a significant impact on your running performance and safety. Learn which temperature ranges are optimal, the physiological risks in the heat or cold, and practical tips to run safely year-round.

1. Temperature Impact Calculator

Discover how many minutes you'll lose on your run due to heat or cold:

Your usual run

Weather conditions

2. Optimal temperatures for running

Scientific studies (El Helou et al. 2012, Ely et al. 2007) show that running performance is maximized between 5°C and 15°C for long distances. Beyond these ranges, the body must devote extra energy to thermoregulation.

Temperature Impact on performance Type of effort
< 0°C Risk of frostbite, vasoconstriction. Performance moderately reduced. Short runs only, very well covered.
0–10°C Good performance. Body regulates well. Ideal for long races (marathon).
10–15°C Optimal zone for most runners. All types of training.
15–20°C Still good. Hydration becomes more important. All types, monitor hydration.
20–25°C Performance starts to drop (−2 to 5% on a marathon). Avoid long intense efforts.
> 25°C Significant risk of heat stroke, major drop (−5 to 15%). Shorten sessions, slow down, frequent hydration.

3. Running in the heat: risks and advice

Physiological effects

  • Increased heart rate: the heart works harder to evacuate heat.
  • Increased sweating: risk of dehydration, loss of salts (sodium).
  • Decreased muscle blood flow: more blood goes to the skin to cool it down.
  • Heat exhaustion risk: nausea, dizziness, cramps, or even heat stroke.

Recommendations

  • Hydrate before, during and after the run (water + electrolyte supplements if >1h).
  • Wear light, breathable, light-colored clothes.
  • Run early morning or late evening if possible.
  • Reduce intensity or distance compared to usual.
  • Listen to your body: stop at the slightest sign of dizziness or extreme fatigue.

4. Running in the cold: risks and advice

Physiological effects

  • Peripheral vasoconstriction: extremities (fingers, nose, ears) at risk of frostbite.
  • Increased respiratory effort: cold air can irritate airways.
  • Greater energy expenditure at the start (warming up the body).

Recommendations

  • Dress in layers (base layer, insulation layer, windproof).
  • Protect extremities (gloves, hat, headband).
  • Warm up longer at the start.
  • If <−10°C, consider very short efforts or alternative (indoor).
  • Breathe through your nose or use a scarf/buff to warm the air.

5. Effect of humidity

High humidity (≥70%) prevents sweat evaporation, which reduces the body's cooling capacity. A humid 25°C is therefore more difficult than a dry 25°C. Conversely, very dry air (<30%) can irritate airways.

  • High humidity + heat: increased heat stroke risk, reduce intensity.
  • Dry cold air: risk of throat irritation, protect airways.

6. Scientific references

  • El Helou et al. (2012) – "Impact of Environmental Parameters on Marathon Running Performance", PLoS ONE: analysis of thousands of marathons showing a drop in performance beyond 15°C.
  • Ely et al. (2007) – "Impact of weather on marathon-running performance", Medicine & Science in Sports & Exercise: confirms the 5–15°C optimal zone for endurance.
  • Montain et al. (2006) – Effects of dehydration and heat on cardiovascular function.

7. Complementary tools

To optimize your running whatever the weather:

Warning

The information provided on this page is for informational purposes only and does not replace medical advice. If you have cardiovascular conditions, respiratory problems or any doubt about your ability to run in extreme conditions, consult a doctor before undertaking physical activity.