Discussion: Temperature

How often do you get a day like that where it basically keeps falling from one midnight to the next?

Depends how tightly you define the question (and Tuesday in Melbourne doesn't really count because it jumped from 30 back up to 36 in the early afternoon ahead of the main front), but probably once or twice a year at most southern coastal locations, more often at really exposed places (like Cape Otway and Wilsons Prom) or mountain tops.

It happens reasonably frequently if diurnal heating is weak enough, whenever a cool change comes through. Hence, Rochester, permanently overcast in winter, is ideal: three times since Christmas already (Dec 28 - falling from -1 to -9.5; Jan 1, falling from +0.5 to -7; and Jan 8, falling from -3 to -9.5).

Do you ever record or report how hot it is in the full sun? When you step out of the shade on a hot day (e.g. crossing the road in the city) it always feels so much hotter - yet presumably both places are receiving the same amount of heat radiated from the environment. And overall there's not much shade in Australia.

It happens a lot more at higher latitudes in winter than it does in Australia - to the point that once you get into, or close to, the Arctic (or Antarctic), the "true" daily range in winter is near zero and temperature changes during the day are driven by air mass changes. You'll quite often see forecasts in Canada along the lines of "temperature falling to minus 6 by evening" or the like.

There used to be some readings made of "temperature in the sun" in the early 20th century; I'm not sure what standards (if any) existed for such observations. Melbourne certainly did them because I saw a reference to them when I was looking at the original journals from 1902 (which are in our library) to get some background on the 1902 night which Tuesday equalled.

So, for curiosity's sake, how hot would you estimate it be in the sun when it is 42 in the shade? And would location make any difference - e.g. in central Australia in the morning it can feel quite cold in the shade and really hot in the sun.