I believe northern lights can stand the weather but, I agree it is getting cold. You have a couple of options. I really like regular gardening - this is my first attempt at ALTERNATE gardening. I have moved mine indoors and used a grow light - to deal with the weather. If you are worried about expense - look at
Welcome to Green's Horticulture - Organic & Alternative Gardening Products they sell the best priced grow tents and lights that I have seen. Sometimes almost half the price of others. You can certainly move them in and out. My problem was the sheer weight of the plant - huge tubs and big branches. You can by horticultural fleece - like the kind of fluffy wadding you have inside jackets and stuff - wrap it around when really cold - I didn't want to do that because I was worried about damaging the trichs. I feel that my plants did best outside - they have great stems! but the weather is not kind. I wish I had started growing when I lived in California - I could have just grown them in the garden!
Good luck