The number that tells you how muggy it really feels.
Enter the air temperature and relative humidity and see the dew point, the true measure of moisture in the air, plus how comfortable it feels and how close the air is to fog and condensation.
The air right now
Relative humidity is what your weather app shows. The dew point below is calculated with the Magnus-Tetens formula (a = 17.27, b = 237.7 °C).
How this air feels
Dew point across every humidity level
Dew point vs relative humidity at this temperature
Reading at a glance
Dew point table
Dew point in °F for common temperature and humidity combinations. Your current column is highlighted.
Dew point, explained
What Is the Dew Point?
The dew point is the temperature at which air becomes saturated and water vapor begins to condense into liquid water (dew). A higher dew point means more moisture in the air. The dew point can never exceed the air temperature.
Dew Point and Comfort
Dew points below 55°F feel comfortable and dry. Between 55°F and 65°F feels pleasant. Between 65°F and 70°F feels humid and sticky. Above 70°F feels oppressive and tropical. Above 75°F is extremely uncomfortable and rarely occurs outside tropical regions.
How Dew Point Is Calculated
The Magnus formula approximates dew point from temperature and relative humidity. First, calculate a gamma value using the natural logarithm of humidity and temperature constants, then apply the inverse formula to get the dew point temperature.
Dew Point vs Relative Humidity
Dew point is a better measure of moisture than relative humidity. Relative humidity depends on air temperature (it changes throughout the day), while dew point directly indicates the amount of moisture in the air. A dew point of 65°F always feels the same.
Common questions
What is a comfortable dew point?
Most people find dew points below 60°F comfortable. Between 60°F and 65°F is noticeable but not unpleasant. Above 65°F feels humid and sticky. Above 70°F is very uncomfortable, and above 75°F is oppressive and potentially dangerous.
Why is dew point better than humidity?
Relative humidity changes with temperature even if moisture levels stay the same. A 50% humidity at 90°F has much more moisture than 50% humidity at 50°F. Dew point directly measures moisture content, providing a consistent comfort indicator.
What causes dew on grass in the morning?
At night, surfaces cool by radiating heat. When the surface temperature drops to the dew point, moisture in the air condenses on those surfaces as dew. Clear, calm nights produce the most dew because surfaces cool more efficiently.
Can the dew point be higher than the temperature?
No. The dew point can equal the air temperature (at 100% relative humidity) but never exceed it. When the temperature drops to the dew point, fog or dew forms. The maximum dew point equals the current air temperature.
Estimates for planning only. The Magnus-Tetens approximation is accurate to within a few tenths of a degree for temperatures from about 0 to 60 °C and humidity above roughly 1%. Actual comfort also depends on wind, sun and personal tolerance.