“Ten below” is, in fact, hotter than any positive temperature on the Kelvin scale.
Nonsense. Kelvin is the same as Celsius but with a different zero point.
+32 F = 0 C = 273 K
Kelvin has no negative numbers because it starts at Absolute Zero. But it goes up as high as any other temperature scale goes.
I’ve always wondered why ≤32F is “freezing.” Why don’t we refer to 32F as “freezing” and <32F as “frozen.”
-21C, actually but that was in January 1795 when London was a rather different place. 
I live about 35 miles from London and it got down to -18C here in winter 1982, when I was five. That’s about half a degree below in Fahrenheit terms… 
Did you click on the link? http://en.wikipedia.org/wiki/Negative_temperature
Do you happen to know when that was? I was in London in December 1976 and it was about that cold then. The Serpentine was covered with ice and there was snow on the ground, but that didn’t deter a couple of boys from playing football dressed in T-shirts and shorts.
I have also had snowfall in London on May 3rd once.
ETA Did you know that Celsius’ original temperature scale had freezing at -100 and boiling at 0? It was later changed by Carl Wilhelm Scheele.
Well, around here (in Oklahoma), temps above 100F are not rare. We typically get three weeks of such temperature a year and this particular year, it looks like we may get far more than that, getting around two months of such temperatures. We may even break records.
To honor Anders Celsius, a Swedish astronomer who defined (almost) the scale that now bears his name — although he had the numbers running in the opposite direction.
Not sure why it’s not “of course.” In Celsius, temperatures aren’t “below” because they’re “below freezing” but because they’re “below zero,” which on that scale happens to coincide with freezing. In Fahrenheit, temperatures “below” are also “below zero”–our zero is simply lower than yours.
I really wish school would have been canceled here every time it hit 5 below. Especially if you factored in windchill. I’m not even sure we canceled recess for that (and if you tried to hang around the bathrooms to stay warm, they’d chase you out).
There are palm trees in Ireland.
Actually, when referring to specific temperatures, I hear anything lower than 32 as “below freezing,” while the general descriptor of “freezing” is not meant to be taken literally and, depending on the tolerance of the person speaking, may be well above 32. For example, while waiting in line at the taco cart outside to get some lunch, I thought to myself, “Man, it’s freezing out here,” when the temperature display I can see from the office says something like 63 (i.e., 20 degrees colder than it has been the rest of the week, and 30 degrees colder than last week).
I’m not sure what that assertion is based on. Leaving aside the fact that people here (UK) would not word it as “ten below” (they’d more likely say “minus ten”), how could anyone know whether they meant below zero or below freezing, especially since they are the same thing? Has there been a poll on the matter?
When I initially puzzled about this, I actually thought that Americans had usefully exploited the fact that the Fahrenheit system has two obvious reference points in that temperature range – zero, and freezing – and so they had two ways of expressing low temperatures in relative terms - “ten below” for below freezing, and perhaps “minus ten” for below zero. Whereas we Celsius users can only give temparatures relative to one point. It turns out not to be the case, but that’s what I was wondering about.
Fair enough.
when I hear it’s ten below in the weather report, all that means to me is put on a coat, cause it’s cold enough to freeze your balls off out there 