Heat Adjusted Pace Calculator
Find your adjusted target pace for running in the heat. Temperature and humidity both increase physiological load — this calculator accounts for both.
The pace you would target in ideal (cool) conditions.
Stay safe running in the heat
Hot weather running demands proper hydration and gear that helps you manage the conditions.
Hydration Vest
Carry water on the move during hot-weather runs. Essential when you need more than a single bottle.
View on AmazonPrecision Hydration
Electrolyte tablets matched to your sweat rate. Replace the salts you lose in warm conditions.
View on AmazonGarmin Forerunner 265
Heat acclimation tracking and real-time heart rate monitoring. Helps you adjust effort as temperatures rise.
View on AmazonHow it works
Heat stress increases cardiovascular load because your body diverts blood to the skin for cooling rather than to working muscles. Research shows performance degrades above approximately 10°C wet-bulb temperature. The calculator uses temperature and humidity to estimate wet-bulb temperature and pace degradation, giving a realistic target for training and racing in the heat.
Frequently asked questions
How much does heat affect running pace?
Studies suggest marathon performance degrades by approximately 1.6–3.2% per 10°C increase above 10°C ambient temperature. At 30°C, that can mean 6–12 minutes slower on a marathon. High humidity amplifies this because sweat cannot evaporate efficiently.
What temperature is too hot to race a personal best?
Most exercise physiologists consider temperatures above 18–22°C suboptimal for racing. At 25°C+, significant performance degradation is expected and most serious runners adjust their targets.
Should I drink more water when running in the heat?
Yes, but individual sweat rates vary greatly. Drink to thirst, aim for 400–600ml per hour as a starting point for moderate heat, and consider electrolytes for runs longer than 60 minutes.