Dew Point Calculator
The temperature air must cool to before its moisture condenses, and what that says about comfort.
What the dew point tells you
It's the temperature at which the air's moisture starts condensing: fog, dew, sweating windows. Unlike relative humidity, it doesn't swing with temperature, which makes it the number meteorologists (and anyone running in summer) actually watch. 25 °C at 60% humidity gives a dew point near 17 °C, the edge of sticky.
Rules of thumb
Dew points below 10 °C (50 °F) feel dry, 16 °C (60 °F) is where most people notice humidity, and 21 °C (70 °F) or more is oppressive. It also predicts the night's low: air rarely cools much below its dew point, because condensation releases heat that brakes the fall. Gardeners use this to see frost coming.