Same With "High In The Upper 30s"

Here’s the problem with Celsius: Zero degrees doesn’t have the same connotation as it does in Fahrenheit 

As opposed to the problem with Fahrenheit in that it's a largely arbitrary measurement?

Fahrenheit is certainly not arbitrary!    The Fahrenheit scale is derived from the temperature delta between freezing water mixed with salt, which was set to 0 degrees, and standard human body temperature, which was set to 96 degrees.  Why 96, you say?  Well, 96 is 12 times 8, which makes it really easy to divide the interval into 12 parts and then each part into 8 segments called degrees.  Based on this scale, the boiling point of water was determined to be 212 degrees.  Later on, more accurate and linear thermometers were developed and body temperature was found to be more along the lines of 98.6 degrees.  

Celsius is just as arbitrary, using water and the earth as the base for measurement (and other measurements, as you may or may not be aware).  It's true.  The entire metric system is based on a single measurement...the circumference of the earth, and a single liquid...water.  A meter was originally defined as 1 ten millionth of the distance from the north pole to the equator.  (The exact definition has technically changed since then, but it's still pretty much the same distance)  Sticking with water, if we arbitrarily decide that the freezing point of water is 0, and the boiling point is 100, then we have the basis for the Cesius, or Centigrade temperature scale...but why use water?  Anyway...one cubic centimeter is the same as one milliliter, and one milliliter of water weighs one gram, so the original distance measurement gives us both volume and weight measurements (under standard conditions, of course), as long as we're still using the arbitrarily decided-upon water.  Going even further, one Calorie (technically kilo-calorie, but that's splitting hairs) is the amount of energy required to heat one milliliter of water one degree C.  The entire system is based on water...which seems a little bizarre.  Sure, it's pretty abundant and essential, but it's far from the most basic thing we have available.  I think a new system should be developed using the speed of light as a basis for distance and Carbon the single element for creating the other measurements.  And start at Absolute Zero for temperature.  Stick with the basics!  (Unrelated, I totally need to start a band called "Minus One Kelvin")  When somebody figures this out, call it the "Jeremy Scale.

So this call comes into play when discussing temperature, particularly outdoor temperature.  When watching a weather forecast in the US, we see temperatures displayed in Fahrenheit.  We're used to it.  We have a feel for it.  When you watch a weather forecast in the rest of the world, the temperature is displayed in Celsius.  They're used to it and have a feel for it.  So why is it more than a simple acclimation time to get used to numbers that mean something different?  Well, for the simple reason of connotation.  When we see a forecast in the US, and the meteorologist says "Zero degrees," or "Sub-Zero temperatures," we know to fear.  The number zero means something to us...that number is synonymous with oppressively cold temperatures.  Zero degrees Celsius doesn't do that.  The freezing point of water really isn't all that cold, in the grand scheme of things.  When it's zero C outside, you're okay with it.  You know you have to wear a coat and maybe a hat and gloves, but there's no abject terror.  For the equivalent in oppressively cold temperatures in metric, you have to go down to -17 degrees.  And that, dear readers, is a really weird arbitrary number to try to remember.