I talked to one of the producers of the film, Mon Mappala, and he told me how Lav had planned to shoot the film in fall, when the leaves were gold and orange. But delays were such that the shoot was moved to winter.
And I think it works out better that way. Gold and orange leaves would have given the film a prettier-looking, more Hollywood-feeling melancholy, whereas there's nothing like winter (and at one point they shot in a blizzard) to really bring out the depth of one's loneliness and depression.