Temperatures below 20F are
not a problem per se. It's possible you ran into Superchargers that were offline, or you may have some issue with your car specifically. As I posted earlier in this thread, I drove from Rhode Island to Cincinnati and back again over Christmas, and encountered temperatures as low as -4F on that trip (on the outbound leg). I Supercharged in those temperatures with no difficulty. Others have posted similar stories, some with Supercharging at even lower temperatures, in this thread. Although it's true that extreme cold (which +16F is
not), or other cold-related weather issues (like Supercharger stalls being buried in snow) can cause problems, I'm skeptical that 16F per se was the cause of your problems. Here in Rhode Island, such temperatures are not uncommon in the winter, and temperature-related problem reports regarding charging are rare.
On my own trip, I
did have problems at the
Washington, PA Supercharger. The first five stalls I tried to use there were down; only the sixth (of eight total at the site) worked. (I don't know about the two I didn't try.) This was on my return trip, and my TeslaFi logs show the temperature was about 29F, so I don't think this was cold-related. I note this to illustrate the fact that, although Tesla's Superchargers have the best reputation for reliability in the DC fast charging industry, they are not perfect, and finding a site with under 50% of stalls working is possible even when it's not very cold.
@Rusty1, can you provide a link to the Supercharger station where you had problems? Perhaps PlugShare check-ins or some further sleuthing would provide a clue about what happened to you.