Weather
The temperature at which dew forms — the single best number for how muggy air actually feels — from air temperature and relative humidity.
| Dew point (°F) | Dew point (°C) | How it feels |
|---|---|---|
| Under 50 | Under 10 | Dry and pleasant |
| 50–55 | 10–13 | Comfortable |
| 55–60 | 13–16 | Noticeably humid |
| 60–65 | 16–18 | Muggy |
| 65–70 | 18–21 | Uncomfortably humid |
| 70–75 | 21–24 | Oppressive |
| Over 75 | Over 24 | Miserable — tropical air |
This scale is the commonly published comfort guidance for warm-weather dew points. Perception varies between people, and in cold weather a low dew point mainly means dry air and static, not discomfort outdoors.
This page uses the Magnus formula, the standard approximation used across meteorology: with temperature T in °C and relative humidity RH, γ = ln(RH ÷ 100) + (17.27 × T) ÷ (237.7 + T), and the dew point is Td = 237.7γ ÷ (17.27 − γ). It is accurate to a few tenths of a degree across normal weather ranges. A built-in check: at 100% humidity the formula returns the air temperature itself — saturated air is already at its dew point.
Why forecasters prefer dew point: relative humidity swings all day as the temperature changes even when the actual moisture in the air barely moves, while the dew point states the moisture directly. Cool any surface below the dew point — a cold drink, a window on a winter night, grass after sunset — and water condenses on it. The temperature–dew point spread also matters in aviation and forecasting: when the spread closes to a couple of degrees, fog is likely.
What is the dew point at 86 °F and 60% humidity? About 71 °F (21.5 °C) — squarely in the "uncomfortably humid" band, which is why that combination feels so heavy.
Can the dew point be higher than the temperature? No — in ordinary outdoor air the dew point is at or below the air temperature, and it equals the temperature exactly when the air is saturated (100% humidity, fog).
What dew point means a muggy day? Around 65 °F (18 °C) and above, most people call the air muggy; past 70 °F (21 °C) it feels oppressive even in the shade.
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