Sun dogs in September? Must be that it's going to be a hard winter!
Hold on! First of all, people need to quit looking for signs about long-range weather predictions because none of them work. Secondly, sun dogs are not a sign of approaching cold weather. They are a refraction of light caused by hexagonal-shaped ice crystals. We see them often in winter when the air is full of windblown snowflakes after a blizzard when it is usually cold. We sometimes see them in winter when it is extremely cold (approaching 40 degrees below zero and the crystals are freezing directly from water vapor in the air).
However, sun dogs can also form from ice crystals in high-altitude cirrus clouds where it is minus 40 degrees or colder, even in summer. Summer (or September) sun dogs are usually not quite as bright as winter ones because the ice crystals are a lot further away. In any case, sun dogs are a sign of ice crystals in the atmosphere, which happens all the time and means nothing about the weather tomorrow or next week or next winter.