Skip to content

Relative Humidity from Dew or Frost Point

Calculate relative humidity from air temperature and a documented dew or frost point, with explicit liquid-water and ice saturation conventions.

Use this result well

Inputs that matter
Air temperature (°C), Dew/frost saturation point (°C), Sources and assumptions
Output to expect
Humidity from dew or frost point
  • Check the units and required inputs before comparing results.
  • Keep the assumptions with a copied result so you can reproduce the calculation later.
Was this tool helpful?

Related Tools

Tools you might need next

Dew and Frost Point with Vapor Pressure

Calculate dew or frost point and vapor pressure using a documented ice/water saturation model, with explicit zero-humidity and range limits.

Recommended next stepMeteorology
Pressure-Aware Wet and Ice Bulb

Calculate pressure-aware wet or ice bulb using station pressure and humidity, with separate phase solutions and clear near-freezing ambiguity.

Recommended next stepMeteorology
Relative Humidity Calculator

Calculate relative humidity from actual vapor pressure and saturation vapor pressure. Free relative humidity magnus tool for relative, humidity, and more.

Meteorology

Reference & details

How it works

Humidity from dew or frost point

Calculate relative humidity from air temperature and a documented saturation point. Below the triple point, the entered point is interpreted as a frost point and the saturation reference is ice.

RH = 100 × es(saturation point) / es(air temperature).

Updated: September 2026

Example Scenarios

Inspect the example and its input basis, then substitute your own documented measurements or matched cases.

Air temperature (°C): 25Dew/frost saturation point (°C): 15

→ 53.812916% relative humidity

Common Mistakes to Avoid

Mixing observation and model inputs

Use the exact units, timestamp, level and measurement or model basis stated by the selected mode. A similar quantity from another instrument or product is not automatically interchangeable.

Treating an illustrative case as a measurement

Replace the example with your own sourced inputs. Retain missing values and method limits, and keep raw source data alongside a saved calculation.

FAQ

Calculate relative humidity from air temperature and a documented saturation point. Below the triple point, the entered point is interpreted as a frost point and the saturation reference is ice.

Retain the station or profile identity, observation or issue/valid time, measurement units, quality flags, source and stated method. Missing values, trace precipitation and known zeros have different meanings.

Save weather case keeps an explicit local record. Copy MD includes current inputs and notes; Download CSV includes the current result breakdown. Keep portable copies separately and retain raw source data.

About Relative Humidity from Dew or Frost Point

Calculate relative humidity from air temperature and a documented saturation point. Below the triple point, the entered point is interpreted as a frost point and the saturation reference is ice.