Earlier quoted context omitted.
I found it a bit clickbaity. The title is correct to the letter but not really to the spirit, because down at the bottom there is: > Temperatures are known to vary wildly over Antarctica, and massive swings are common. Contrasting with this warm spell over eastern Antarctica, the South Pole observed just observed its coldest April to September period on record last year, with an average temperature of minus-78 degree…
I think you're hearing "massive swings" and jumping to the conclusion that 5 std dev is somehow normal-ish behavior for the region. It's not. At all. By definition.
[1] https://en.wikipedia.org/wiki/Log-normal_distribution
From this vantage point, bigger positive swings are more likely than bigger negative ones - because positive swings are in the range exp(logmean)..infinity and negative ones are in range 0..exp(logmean).
Take a look at second picture in Wiipedia article. The value with CDF(x)=0.75 is about four times bigger for sigma=1 curve than value for CDF(x)=0.25.
And I guess that distribution of temperature in Antarctica is more close to a log-normal distribution than distribution of temperature in, say, Houston or Cancun.