For all practical purposes, ejected droplets in my climate at ambient temperature in the winter form particulates. I have seen both spit and urine freeze on the way to the ground.
This also raises the question of viral longevity at low temperatures (subzero Fahrenheit), because for all practical purposes the ejected virus would be contained in a particle of ice.
With temperatures of -30F and wind speeds of 20 MPH considered a relatively normal day, those will likely get mixed in with the finely powdered snow which is normal here.
The joke is that the snow doesn't melt, it wears out on its way to Minnesota. In reality, it sublimates, which would eventually leave the little virons naked and freezing, stuck on a surface somewhere.
Keep in mind that solar angle is low (and so is UV), and that daylight hours are down to eight or so in midwinter. There is plenty of shade.
This raises questions, should an outbreak make its way here, of how long the virus would remain viable in such environs. Similar concerns have been raised by people in slightly milder climates, and I think they have raised a valid question.
As far as I know, there is no data which could conceivably predict that, but lingering 'frozen particulate fomites' could present a hazard to emergency personnel (especially near hospital entrances) and to the casual passerby in any location where the virus has been shed.
We become acclimated to such temperatures fairly readily (kids ride their bicycles in the snow in that weather), although the relatively dry air often wreaks havoc with sinuses and air passages.
The combination of irritated pharyngeal mucosa and readily inhalable frozen particulates is an unknown, but may present a hazard that cannot be extrapolated from tropical data.
Ebola is an RNA virus.
Knowing how fragile RNA is, and the wide range of stability of proteins, I doubt that virus would be able to survive in those conditions. When you work in a lab, for instance, extracting RNA from Ebola viruses for PCR analysis, you go through a pretty ornate ritual to remove from the environment anything that could damage the samples. You wash the glassware with a special detergent, and rinse it with water that has been processed to remove anything that can damage RNA. You wash down all of the bench surfaces with a chemical to destroy anything that might damage RNA. You buy disposable lab supplies that are certified RNase and DNase free. You dedicate lab equipment for the purpose of analyzing RNA, and you never contaminate that equipment by using it to analyze any other type of biological molecule. People who work with RNA are extremely paranoid about anything that can destroy it, because it is so fragile. Your skin is saturated with enzymes that kill RNA, and those enzymes tend to be all over. Even when you put RNA into a special stabilizing solution, it has a shelf-life--about one month at -20C. When you put the purified samples in a -70C or -80C freezer, they last indefinitely--but once you remove them, you have to complete your analysis on them, because the RNA is not stable enough to freeze the leftovers for further analysis.
Proteins range in stability, but even the extremely stable proteins do not survive multiple freeze-thaw cycles. Changes in temperature are very destructive to any biological molecule.
Another RNA virus is rabies, which is endemic across the US. I have never heard of a case where rabies was transmitted by droplets of frozen saliva. Certainly, if rabies could transmit in that fashion, we'd have a lot of cases where someone out tramping through the snow in the winter kicked up a powder, or brushed their shoe, or otherwise made contact with virus-laden bits of ice. If rabies could transmit in that fashion, rabies would be a huge problem because of its endemicity. No one would know they'd been exposed, and so wouldn't get the prophylactic treatment. But rabies is not transmitted like that--the only way to get rabies is through direct contact with the saliva of an infected animal. All it has to do is enter through a break in the skin.