What is dew point?
Dew point is the temperature to which air must cool for water vapour to begin condensing into liquid water. When air temperature and dew point are close together, the air is nearly saturated and fog, dew or low cloud becomes more likely.
Unlike relative humidity, dew point is an absolute-feeling measure of moisture in the air. A 70% relative humidity reading can feel very different on a cold day and a hot day; the dew point makes that difference easier to compare.
How this dew point calculator works
The calculator uses the WMO saturation vapour pressure approximation over water, with constants 17.62 and 243.12°C. It is designed for normal surface-weather conditions. Measurements from a calibrated weather station will always be more precise than values calculated from rounded inputs.
How to read the result
- Below 10°C / 50°F: usually dry or crisp.
- 10–16°C / 50–61°F: generally comfortable.
- 16–21°C / 61–70°F: increasingly humid.
- Above 21°C / 70°F: muggy for many people.
Comfort is personal and depends on wind, sunshine, activity and acclimatisation. Use the result as a practical comparison, not a health threshold.
Frequently asked questions
Is dew point the same as humidity?
No. Relative humidity changes with temperature, while dew point describes the actual moisture content of the air in temperature terms.
Can dew point be higher than air temperature?
In ordinary surface observations, dew point should not exceed the air temperature. Small differences can appear because of sensor or rounding errors.
What dew point feels uncomfortable?
Many people begin to notice humidity around 16°C or 60°F, while dew points above 21°C or 70°F often feel muggy.
Method and sources
Last reviewed: July 11, 2026.
