Let me preface this by saying I have been to 27 countries, and have lived all over the U.S. Wherever I have been, I usually have heard some variation on the phrase, "If you don't like the weather here, wait five minutes and it will change." Usually, there is little truth to this.
I am kind of a weather "buff". So, when I was getting ready to move to Colorado from Cali, I did some research. Wow.

That saying definitely applies more to the Front Range weather in Colorado than just about anywhere.
http://denver.cbslocal.com/2018/02/20/big-temp-swing-in-denver/

MN gets some pretty wild swings in temp too. A/C one minute and furnace the next.

I'm about to take a half-day and go home and enjoy this. This is the first winter in about twenty years that I've been able to bike in January. 70F? Totally going to make the most of the day. Roads will even be dry.

It is not just the temp swings. A couple of years ago, I came home about 5 in the morning. My street is about 100 yards long. It was snowing on my street heavily(ended up being about 1.5 inches), and not at all on the streets on either side. I have seen it snow(and rain) on a clear blue, not a cloud in the sky day. I have seen lightning strikes, on a clear blue, not a cloud in the sky days(storm is 40-50 miles away). That is why in the summer, you don't go hiking in the mountains after 11:00 a.m.

Texas has had the weirdest winter I have felt in 6 years down here.

Snowfall 3 times, measurable snowfall twice.

Ice on several occasions.

80 degree heat, swings to upper 30's in 12 hours.

I ran the AC last night it was super humid and 75 degrees in my house. This morning we work up and had to run the furnace it was 65 degrees because it was under 40 degrees outside.

We was out there last summer. Landed in Denver and made our way up to RMNP. Go from sweating down at 5-6k elevation to needing the winter coat at 12k. That must play havoc on weather there.

We say that about STL. We can have a 40 degree temperature swing in a day. But probably not as drastic as the Denver/Boulder area.

I have a theory:

Wild temp swings increase flu cases and upper respiratory problems.

The Front Range is unique.

I've lived all over the country, and I've seen lots of things, like a thundersnow, or 80 MPH adiabatic winds, that happen ONLY in the Front Range.

Auckland separates the Tasman Sea and Pacific Ocean by only a few hundred metres, weather passes over like a land mass isn't there, unpredictable, and gets hit by big storms when they come across. In Melbourne they talk about the cool change, and it can be extreme. As an Aucklander (jafa here) I was prepared for weather changes, but in Auckland the weather changes, but the temps don't. In Melbourne the weather stays the same, but the temps change - go out in a T shirt, and a couple of hours later you are shivering, or the other way around.

Weather is very stable here in the desert southwest. 300+ plus days a year of sunshine. Yes summers are very hot, but rarely get wild temp swings regardless of the season. A temp change of plus/minus 10 degrees is usually considered a big change in the weather.

^^^ Sounds like Texas!! ^^^

Mountain ranges have the ability to wreak serious havoc on the weather.

I can't understand how it can be clear blue skies full of sunshine and then have the highest temp reach 50 F.

Here we can have a clear blue sky and bright sun and -35 C. Clouds tend to act as an insulating blanket trapping some heat, so it's rarely that cold when it's not clear.

A hill by a river valley on a clear night will cause the cool air to settle in the valley at the bottom of the hill.

PS. it was sunny and hit 73 here today.