A real-time contrail likelihood forecast built on live atmospheric data from the Open-Meteo API. Checks relative humidity at cruise altitude (200–300hPa) across daylight hours and tells you whether persistent trails are likely, short-lived, or improbable — in 3-hour slots, up to 5 days ahead.

If someone points at spreading contrails and says something suspicious is going on, pull this up. If the humidity was high and persistent trails were predicted — that's atmospheric physics. That's what this tool shows.