Fog Calculator

Calculate fog probability and visibility conditions

Understanding Fog Formation

Fog forms when the difference between air temperature and dew point is minimal, typically accompanied by high relative humidity. Understanding these conditions helps predict fog formation and its potential impact on visibility.

How to Use the Calculator

  1. Enter the current air temperature
  2. Input the dew point temperature
  3. Specify the relative humidity percentage
  4. Enter the current wind speed
  5. Select your preferred unit system

Understanding Results

The calculator provides:

  • Fog probability percentage
  • Expected visibility range
  • Condition analysis
  • Formation and dissipation timing

Key Concepts

Temperature-Dew Point Spread
Smaller spread increases fog likelihood
Relative Humidity
Higher humidity (>90%) favors fog formation
Wind Speed
Light winds (<5 mph) often ideal for fog development