So, after I’ve disproven the “Thunder in February, frost in April” aphorism, I’ve seen people trying to suggest that instead it is actually supposed to be “thunder in February, cold front in April” or “thunder in April, cold front for the South.”
Oh. Well when you put it that way….
It is still wrong. Sorry.
Correlation does not equal causation
That is another saying. It is actually one that is factual, though. Here is a good example of things that share a correlation, but there is no causal relationship:
Obviously, the amount of cheese people eat does not – in any way – cause people to die from being tangled in their bed sheets. Just because two things can line up, doesn’t mean they are connected.
Here is another example:
Here is another example a bit closer to home….
The correlation is nearly perfect! A 0.992835 is incredible.
But the two are n not related. Milk consumption and marriage do not have any connections.
Is February thunder and April cold correlated?
Not really.
Looking back at the recent data – 2016, 2017, 2018, 2019 and 2020 – I looked to see how many times there was overlap between days in February where it was warmer than 60-degrees with precipitation (thunder) and days in April preceding a cooldown of greater than 3-degrees (cold front). This data is for the Bobby Chain Airport in Hattiesburg, Mississippi.
Was there overlap? Sure. There were seven times during the 54 possible days that the two dates could overlap. So it was right about 13-percent of the time.
Not very accurate. That is about one out of every eight attempts.
Were there days it was close? Sure. It got within one day on 17 out of the 54 possible days – about 31-percent of the time.
But something that is only accurate once out of every three attempts isn’t that accurate, either..
Is there a better way?
Perhaps. Instead, of relying on days with thunder two months prior, it might be better to look at the dates of the cold fronts during April and try to pick out if any pattern shakes out.
When taking the average date of the first, second, third, and fourth cold fronts during April you get April 4th, 11th, 15th, and 22nd.
Looking at those dates, you may quickly realize why the “thunder in february (frost/cold/etc)” came to be. Because, generally, all winter long and into Spring cold fronts pass through the southeast about every four to seven days. And the interval between the average dates for cold front passage in the statistics we looked at is also between four and seven days.
But we need to look even deeper. We need to look at the variability of cold front arrival between the years. this will help us get an idea about how likely the cold front is to show up on that specific day. And also an idea about the spread between the data.
So we look at the Standard Deviation.
| Average date | St Dev | Arrival Range | |
| 1st Cold Front | 4th | 3.03 | 1st – 7th |
| 2nd Cold Front | 11th | 3.57 | 7th – 15th |
| 3rd Cold Front | 15th | 3.71 | 11th – 19th |
| 4th Cold Front | 22nd | 5.49 | 16th – 28th |
The Standard Deviation lets us know about the variability between the arrival date of each successive cold front. Notice that the first cold front will arrive some time between the 1st and the 7th, the second right on it’s heels between the 7th and the 15th. The third cold front, though, can arrive as early as the 11th or as late as the 19th.
The fourth – and sometimes final – cold front can arrive as early as the 16th or as late as the 28th. Generally, when the fourth cold front arrives earlier, there is a fifth cold front that shows up. That cold front generally arrives between the 20th and the 26th.
This is an actual forecast you can count on. It isn’t as precise, but it is far more accurate. And I can prove it. I went to google to pick a random number between 1919 and 2020
It gave me 1944. So, I went back into the record books.
In 1944 the cold fronts arrived…
| Arrival Prediction | Actual Arrival | |
| 1st Cold Front | 1st – 7th | 2nd |
| 2nd Cold Front | 7th – 15th | 12th |
| 3rd Cold Front | 11th – 19th | 17th |
| 4th Cold Front | 16th – 28th | 22nd |
MATH! FOR THE WIN!
And I didn’t have to reference thunder in February at all. In fact, using the same method as above, looking at the February data for 1944 there was thunder on 13 days! There was likely thunder recorded on 3rd, 4th, 9th, 11th, 17th, 18th, 19th, 20th, 21st, 22nd, 25th, 26th, 29th
And I find it unlikely that there would be 13 cold fronts moving through in April. That would be one nearly every other day. And you can compare the dates above to the chart of daily temperatures in April. There is no real relationship at all between the 13 days of thunder and the warmth – or lack of warmth – on certain days in April.
I trust my PawPaw over you, Nick
That’s fine. Look, I’m not here to attack anyone’s choice. But I do doubt anyone (but me, probably) has every taken the time to lay all of this out and help everyone understand the uselessness of a lot of ‘old wives tales’ that are tossed around.
Now that you know it isn’t scientifically or mathematically useful, if you choose to continue to believe it, that is fine.
And actually, one of my my grandpas was a farmer. And he told me a whole slew of ‘old wives tales’ about weather and loose predictions for the future weather based on random weather events.
Was he wrong? Yeah.
Did that mean I loved him any less? Not at all.
I recognize that those sayings were the only thing that he could use to explain what he saw and experienced. And it was the same for his father and grandfather before him. He wasn’t paying as close attention to the weather as I was, because he was busy with his soy beans and cattle.
And the “early weeds, early seeds” type things were good enough for him to ballpark certain events. If they were wrong, he would adjust. But, I will say, he would rarely remember when they were wrong.
Because they were wrong every year. Either that, or they didn’t relate to each other.
And the next year, he would say the same thing. So I get it.
I’m certain I just went through this whole thing and a lot of you are looking at this going, “Nah, Nick’s wrong. The wives tale nailed it last year.”
One thought on “Thunder in February, (insert assertain here) in April”
Comments are closed.