Well, warm is relative. :) When you get up to the areas under the auroral zone where it is more frequently visible, it is going to be cold. Summer time, when temps would be warmer, is too bright in the region. If you go further south, you may be able to see aurora during peak activity times even in the summer, because it gets dark enough.
I looked up the average temps for Dec 28 for some locales (https://weatherspark.com/)...
Reykjavic, Iceland: 0 deg C / 32 deg F
Tromso, Norway: -3 deg C / 27 deg F
Fairbanks, Alaska: -20 deg C / -5 deg F
Churchill, Canada: -23 deg C / -10 deg F
Cloud cover is another consideration to look into.
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My profile has many shots taken at various times of the year, when storms are forecast. I live in Canada, and get several opportunities a year to get out on short notice. I haven't yet been somewhere "exotic" for a trip to see the aurora. I usually just go 1-2 hours drive from home to find somewhere interesting to take photos.