Humidity & running
Running in high humidity
By Iustin Nita · Updated
Dew point, not relative humidity, decides how hard a humid run feels. Below 55°F (13°C) dew point running feels comfortable; from 64°F (18°C) cooling starts to lag; above 70°F (21°C) the air is oppressive and sweat drips instead of evaporating; 81°F (27°C) is a hard safety gate. When it's high, hold effort and let pace go.
Humidity is the most underrated factor in running. Two days at the same temperature can feel completely different depending on how much moisture is in the air, and the number that captures it is the dew point. The dew point is the temperature at which air becomes saturated; the higher it is, the less your sweat can evaporate, and evaporation is how you cool down.
A rough scale: dew points below 55°F feel comfortable, the 60s start to feel sticky, and anything above about 70°F is oppressive: the air is so wet that sweat just drips instead of cooling you. At that point your core temperature climbs, your heart rate drifts up, and holding your normal pace takes far more effort. Relative humidity percentages are misleading because they depend on temperature; dew point is the honest signal, which is why RunWeather scores it directly.
When the dew point is high, treat pace as the variable and effort as the constant: ease off, run by feel or heart rate, pick the time of day with the lowest dew point (often just before dawn), and hydrate aggressively. The month-by-month breakdowns on each city page show exactly when the sticky season hits where you run.
What dew point is too high for running?
The five dew point bands the RunWeather scoring engine uses. The same cutoffs apply in the app, the calculator, and the heat-risk board.
| Dew point | Band | Effect on your run |
|---|---|---|
| Below 55°F (13°C) | Comfortable | Sweat evaporates freely; humidity is not a factor. |
| 55°F (13°C)-61°F (16°C) | Pleasant | Barely noticeable moisture in the air. |
| 61°F (16°C)-64°F (18°C) | Noticeable | Cooling lags on harder efforts; heart rate drifts. |
| 64°F (18°C)-70°F (21°C) | Sticky | Sweat starts dripping instead of evaporating. |
| 70°F (21°C)+ | Oppressive | Seriously harder effort at any pace; slow down and shorten. |
| 81°F (27°C)+ | Hard safety gate | Score is capped as unsafe regardless of acclimatization. |
These cutoffs come straight from the scoring engine. The full model, including safety gates and the performance/safety/experience blend, is published at How the Run Score works.
Most humid cities to run in
Ranked by the typical dew point of each city's most humid month.
How running weather works
Go deeper on the mechanism: what the numbers do to your body, and what to change on the day.
More running-weather guides
Get this on every run, automatically
RunWeather syncs with Strava, plans your week, and learns your heat tolerance, so the right time to run finds you. Free on iPhone and Android.