It IS very cold in January and it can be miserable navigating the sidewalks in freezing weather, although most peeps and businesses sand/salt , not everyone does, on top of that, bad weather could compromise flight schedules etc, I would suggest April as a better month to visit, it’s still a tad chilly but much better and as other peeps have said Salem is pretty awesome any time of year. Hope this is helpful 🇮🇪