It depends on your camera too, how much it can handle higher ISO. My old one was quite bad at 5000(extremely noisy)and I had to use longer shutter speeds like 6 or 7sec, so I could use lower ISO like 2000.
To track northern lights activity I use Space Weather Live app, can also be watched on pc.
It usually sends an alert on my phone about the current KP index, which tells me generally how strong the storm is, like right now for example.
If there is good activity going on, I look for local cloud forecast, if I have clear sky or at least somewhat clear, then I’ll check out different metrics in the app if it’s worth driving to somewhere dark. Usually I check out these indexes. Hemispheric power near 100 is very promising but yesterday it was only 70 for example.
There is a couple of more I look at when deciding to drive out. Still, there is never a guarantee, I might sit for hours and see nothing besides a faint glow, or sometimes get very lucky. Northern lights can appear in seconds and be gone in seconds as well.
Tonight is quite promising too, but Estonian cloud forecast is pretty bad tonight so I won’t bother.
I am going to have to test my camera a bit, as I rarely use high ISO. It should be pretty decent, but let's see!
Thanks again for the info and suggestions. I will start digging around.
(The clouds are rolling in here too)