Dew Point vs Relative Humidity: The Math Behind How Weather Actually Feels

Relative humidity (RH) is a percentage that compares the current moisture in the air to the maximum amount of moisture the air *could* hold at that specific temperature. Because warm air can hold exponentially more moisture than cold air, a 90% RH reading on a frosty 32°F morning holds less actual water vapor than a 50% RH reading on an 85°F summer afternoon.

Dew point, on the other hand, is an absolute measure: the exact temperature to which air must be cooled for water droplets to condense. When dew points rise above 65°F (18°C), the air feels sticky; above 70°F (21°C), sweat struggles to evaporate. For quick conversions between Celsius, Fahrenheit, and metric units, check out our Unit Converter.