It’s not spring yet, so please stop flouncing about like a newborn lamb. Thank you

SPRING has sprung. Or has it? The b-a-a-a-a-d news is that September 1 is not the start of spring. Here’s why.

Collingwood Children's Farm. Newborn Lambs.

SPRING has sprung. Or has it?

Here in Australia, most of us consider September 1 the first day of spring. It’s nice and warm on the east coast today too, so there’s every reason to feel happy and flounce about like a newborn lamb.

But technically speaking, spring hasn’t quite sprung yet. Not if you follow the astronomical calendar, anyway.

In the truest sense, spring starts on or around September 21 (the date varies by a day or so each year), This is known as the spring equinox, and it heralds the day when the southern hemisphere receives more sun than the northern hemisphere.

For the record, this all happens because of the 23.5 degree tilt of the Earth’s axis, but we don’t want to bog you down in science.

MORE: Get your 7-day forecast by state

What you need to know is that astronomically, it’s not actually spring yet.

It is, however, officially spring according to the people who rather matter on these issues, and here we speak of Australia’s venerable if occasionally inaccurate Bureau of Meteorology.

It’s too early for these. No poetry either, please.

As BoM senior climatologist Kevin Smith told news.com.au today, spring starts on the first day of the month for ease of record keeping more than anything else.

“Today is the first spring, which sits with our calendar. It makes it nice and easy for everybody, and we’ve been starting the seasons on the first of the month for as long the Bureau has been taking records.

“If you started making seasons from the 21st to the 21st you’d probably end up confusing people.”

So there you have it. Spring starts on the first of the month so nobody gets confused. So does summer, autumn and winter. But that doesn’t mean that’s actually when the seasons start.

Think about it intuitively for a moment, and answer this question. If you live in the southern half of Australia, do you think it’s hotter in (A) December, January and February, or (B) from around December 21 to March 21? You’d answer B, wouldn’t you?

A quick look at capital city average temperature data confirms that March is almost identical to December in terms of average maximum temperatures. Indeed, there’s less than half a degree difference in the December/March averages for Sydney, Melbourne, Hobart, Adelaide, Perth and Brisbane.

I don’t mean to be the black sheep in the family, but I had my ears out and overheard the conversation. What the hell do you mean it’s not spring yet?

Interestingly, many other countries use the astronomical calendar for their seasons. Even the USA, which is famously old school with its imperial measurements and Fahrenheit temperatures, starts the seasons on or around the 21st.

Does that mean we Aussies and our weather bureau are misrepresenting climatic reality?

“No,” says Kevin Smith firmly. “We stick to calendar months because it works nicely for everybody.”

Oh, and just in case anyone doubts that wintry weather can still strike in September, a strong cold front has moved through Western Australia and South Australia this week, and is set to affect NSW, Tasmania and Victoria later today and tomorrow, with the best snowfalls in weeks on the Alps.

Originally published as It’s not spring yet, so please stop flouncing about like a newborn lamb. Thank you