Showalter Index Calculator

Dangerous Heat Builds and Expands; Critical Fire Weather for the Southwest; Severe Thunderstorms for Plains and Midwest

Dangerous to record breaking heat will build across the center of the nation and slowly build eastward this week. Wildfire conditions remain critical for the Southwest and portions of the Great Basin through Monday. For the northern Plains and upper Midwest, severe thunderstorms with the potential for large to very large hail and severe winds are the primary hazards. Read More >

Showalter Index

Enter the temperatures that you would like:

What does my answer mean?

Showalter Index greater than 0: Stable, but weak convection possible for SI = 1-2 if strong lifting is present.
Showalter Index between 0 and -3: Moderately unstable.
Showalter Index between -4 and -6: Very Unstable.
Showalter Index between less than -6: Extremely Unstable.

Dangerous Heat Builds and Expands; Critical Fire Weather for the Southwest; Severe Thunderstorms for Plains and Midwest

Showalter Index

by Tim Brice and Todd Hall

Enter the temperatures that you would like:

What does my answer mean?

What is the formula for the Showatler Index?