IonoFlux field guide
Solar wind and Bz
Solar-wind speed and Bz explained without space-weather jargon.
In simple terms
Solar wind is a stream of charged particles flowing past Earth. Bz is the north–south direction of its magnetic field; sustained southward Bz often couples more strongly to Earth's field.
How to read it
Use speed and Bz as context for changing geomagnetic conditions. They are warning signs, not a direct band-open/closed switch.
A practical example
A fast wind stream with southward Bz may be followed by a Kp increase. You may see paths become less stable before the daily averages fully reflect it.