Using barometer to predict weather

[Cuspid]

I’ve recently bought a Garmin smartwatch with ABC capabilities. I used to have a Shinto Core a few years back with the same features. Both watches include a function to warn you if there is an impending storm, but on the Garmin you can actually define the rate of pressure change which would trigger said warning. For those living in Gauteng, and Johannesburg in particular, what have you found to be helpful about your barometer readings, and have you been able to correlate the correct rate of pressure change which usually results in precipitation?