I’m new to Home Assistant. How would you define an automation or alert around a short term drop in barometric pressure? I have the pressure data coming in from OpenWeatherMap.

Derivative looks like just what I need. I assume it’s going to take some time to collect data once I create it correct?

Haven’t actually used it myself.

Not really but it depends on how you have the sensor configured.

here is an example of the rate of change of the temperature of my fish tank:

```
- platform: derivative
source: sensor.tank_sensor_temperature
name: Tank Temperature Derivative
round: 3
unit_time: h
time_window: "00:30:00"
unit: '°F/Hr'
```

here is a graph of the result:

and here is the temperature graph that sensor is based on:

That graph looks like an offset rather than a derivative (rate of change)?

oops, you’re right. That was the wrong graph.

Corrected above now.

Thanks for pointing it out.

It did take a little while for the derivative sensor to begin reporting data.

I’ll watch it for a few days and try to find a threshold for predicting storms.

Thanks for the help!

well, sure it has to have some historical data for the calculation but not much for a small window.

post back your results. I’d like to see what you can do with it myself. Sounds interesting.

And compare it to a weather forecast sensor??