Humidity & running
Running in high humidity
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.
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The numbers
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.
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 drink to thirst rather than forcing fluid, since overdrinking is its own risk. The month-by-month breakdowns on each city page show exactly when the sticky season hits where you run.
For effort and pace-target context, read how much slower to run in heat and humidity and the dew point running chart.
Most humid cities to run in
Ranked by the typical dew point of each city's most humid month.
Keep going
How running weather works
Go deeper on the mechanism: what the numbers do to your body, and what to change on the day.- What to Wear for a Cold Marathon Start, by Goal Time
- What to Wear Running in Cold Weather: Wind, Wetness and Waiting
- How Cold Is Too Cold to Run? The Limit Is Wind Chill on Bare Skin
- Running in the Dark: Reflectors on Your Joints Beat a Vest
- How We Price Race-Day Weather, and the Two Things We Got Wrong
- Same Temperature, Different Run: 684 City-Months of Running Weather Data
- Dew Point for Running: The Chart, and Why It Beats Humidity
- Best Time of Day to Run in Summer: Read the Dew Point, Not the Thermometer
- How Much Does Heat Affect Running Pace?
- Hydration and Sodium for Hot Runs: A Dew Point-First Plan That Avoids Overdrinking
- Treadmill vs Outdoor Running: A Weather Decision Guide
- What to Wear Running in Heat and Humidity: A Dew Point-First Gear Guide
More running-weather guides
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