 | The Kp scale. Higher the Kp the better chance you have of seeing the Aurora. Spaceweatherlive.com widget changes colour the stronger it gets. More detailed information https://en.wikipedia.org/wiki/K-index |
 | Solar Wind Speed. When a solar storm hits the wind speed will step up. This is a great sign of a storm hitting. Higher the number the better. More information https://en.wikipedia.org/wiki/Solar_wind |
 | Solar Wind Density The solar wind density is also a good number to watch as a storm hits the numbers will step up. Again higher the number the better- |
 | Magnetic Field Bz The Bz fluctuates all of the time. I have personally found that when it goes in to -Bz it northern lights are more active. I am willing to be corrected on this. Magnetic field – Wikipedia |
If the Kp is high, solar wind speed and density are high and the Bz is in a minus figure.
You will have a very good chance of seeing northern lights.
3 Out of 4 on Spaceweatherlive
This is an observation that I and a few other northern lights photographers have noticed. In Uusimaa southern Finland on rare occasions it is possible to see northern lights with a low Kp. With very high wind speed, density and a -Bz the Aurora can be visible at Kp2 as far south as Loviisa.
So if 3 out of the 4 are high check a webcam from our list https://anthony.fi/aurora/best-aurora-links/ this will save you from getting cold while waiting to see something.