Best place to be: A landfill, probably, since her noxious fumes might allow the garbage to decompose more quickly and add more room for new garbage.
June Gloom can turn the brightest apple into a drab, blackened shadow of its former shell, all plants wilt and turn black, animals turn grey, water becomes foggy grey-blue and the sky becomes deep gloomy gray.
Best place to be: A graveyard, to maintain the dark and creepy atmosphere, or goth hangouts.