no, cannabiswill flower when you give it 12-13 hrs of darkness at any time of the year. but, if the light isnt strong, ie like in the summer, you wont get the large flowers you would if you did it in summer.
many growers do this during the end of summer to make sure they get a harvest from them where if they had relyed on the natural light hours depleating, they risk getting caught out by bad wether and bud rot sets in.
and as long as it has 5 hrs of direct sun shine a day and 4 hrs of lower daylight, it will grow well
soo you can flower 12/12 from seed if you want, but most people let the plant grow for a time and then do the bringing it inside to flower, keeping the plant small but fully flowered