Rule of thumb · EnvironmentalNº 06 / 167

Dew point is the comfort number

Dew point above 20 °C feels oppressive to most people; below 10 °C feels dry.

Why it works

Dew point measures absolute moisture, which governs how well sweat evaporates. Relative humidity alone misleads — 90% RH on a cold morning is comfortable.

When it fails

Acclimatisation moves the whole scale: 22 °C dew point is routine in Singapore and floors a visitor from Scotland. And it only describes still air — 24 °C dew point with a breeze and shade is bearable, while 18 °C in direct sun with no air movement is not.

Do it exactly

Estimate with the rule, then check it against the calculator that models it properly.

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What dew point feels humid?

Dew point above 20 °C feels oppressive to most people; below 10 °C feels dry. Dew point measures absolute moisture, which governs how well sweat evaporates.

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