So I will be flying into buffalo in January for an interview. Is the place usually coated in snow during that time? If it is then I would buy southwest in so that I could reuse the money in case my flight is canceled. If not then I would go with another cheaper airline company.

I thought most airlines have some sort of policy in place to protect you if your flight is cancelled due to weather? Anyways I've flown in and out of Buffalo several times during the winter and never had any problems. The airport is north of the city and most of the snow hits the "southtowns" the hardest. I think they're pretty good about dealing with bad weather there even if it hits. On the other hand if you have any other potential interviews in the days surrouding this interview you may want to buy Southwest anyways just so you can change your itinerary if you need to.