Planning a week for auroras in Inari
The first time I went to Inari I checked the Kp index every twenty minutes and saw nothing for four nights. The sky was covered the whole time. On the third trip I stopped looking at geomagnetic forecasts almost entirely and planned around cloud cover instead, and that week I saw something on five evenings out of seven.
The Finnish Meteorological Institute publishes a cloud forecast with good resolution for Lapland. I keep two or three locations within an hour's drive and pick the one with the clearest window after 21:00. In practice a Kp of 2 over a clear lake beats a Kp of 5 under a grey lid every single time.
Where to stand
Anything facing north across open water works. The shore near the Siida museum is convenient but has light from the road. A few kilometres along the Menesjärvi road there are lay-bys with a dark view over the lake. Bring a headlamp with a red mode and switch it off once you've set up.
Cold and batteries
In late October the nights were around minus eight. Camera batteries lasted roughly forty minutes outside of a pocket. I rotate three, keeping the spares inside my jacket. A thermos and a sitting pad make the waiting much easier than any piece of photo gear.
Settings that worked
Most frames were 8–12 seconds at f/2.8, ISO 1600–3200, focus set manually on a distant light and taped down. When the arc started moving faster I went shorter, around 3 seconds, so the curtains kept their shape.