There are many apps available that can provide you information about the solar activity and chances that you have to see the Aurora. All apps will provide you with KP Index, BZ, BT, Solar Wind and some with cloud coverage, based on the combination of the values they provided a % of chance that you have to see the Northern Lights.
The KP index is one of the most known data for aurora. Related to the disturbance in the Earth’s Magnetic field, it expresses the scale of activity on a level from 0 to 9. The higher it gets, the more chance you will see the Northern Lights far from the center of the Pole. Even though KP index is a very popular data among aurora hunters, unfortunately, it has proven to be wrong many times as it only compounds the Northern Lights’ strength for the next 3-6 hours.
IMF Direction (Bz value)
It is the substance ejected by the sun, and it’s called Interplanetary Magnetic Field or IMF. The IMF enters either from the North or South magnetic pole of the Earth.
To see aurora you need the Bz direction to be negatives (southward). The negatives Bz means the particles have been pushed toward the earth and creating the glowing light which we see as aurora. You are still able to see aurora when the Bz is not negative or around the 0nT, but it will be a less show.
IMF Strength (Bt Value)
Like above it is the substance ejected by the sun called IMF. It arrives with a certain strength on Earth.
To see bright Northern Lights you need the strength (Bt) to be positive. The stronger it gets, the more intense you will be able to see the aurora.
The solar wind is the stream of energetic particles that flow outward from the sun. The faster it gets the stronger aurora you will see.
The clearer the sky is the more likely you will see the aurora and get a clear picture of it.