The 50th anniversary of the Bureau of Meteorology of the switch from “sudden death” from Fahrenheit to Celsius

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Fifty years ago on Thursday, the way we describe the weather changed overnight when the Bureau of Meteorology (BOM) switched from Fahrenheit to Celsius.

The change was part of Australia’s conversion to the metric system, overseen by the Metric Conversion Board.

And while the overall change was a daunting task, the transition was seen as fairly seamless.

Retired meteorologist Mike Bergin, who was training with BOM at the time, said one of the main talking points was whether or not to eliminate Fahrenheit.

“And in the end, the decision was made that on the first day of September, we’re going to do cold turkey, and that’s the end of Fahrenheit, and we’re starting with Celsius.

“So for a lot of people, I’m sure it was quite a dramatic decision.”

Standard body temperature dropped from 98.6 degrees Fahrenheit to 37 degrees Celsius.(ABC News)

Converting from Fahrenheit to Celsius was no small feat.

To do this, the BOM replaced 6,000 Fahrenheit thermometers and recovered the mercury.

They also had to convert 15 million historical temperature records from Fahrenheit to Celsius.

Catchy jingles replace the magic

And then there was the task of changing the language in everyday life.

“The only thing I remember was that it was 100 degrees Fahrenheit [thought as] some kind of magic, it’s super hot, number,” he said.

“Of course it converts at a very awkward 37.78 degrees Celsius, so it loses its magic.

“But I think maybe 40C has become the ‘oh, my God, that’s really hot’ point.”

An old BOM brochure describing the feel of degrees Celsius
To help people adjust, the BOM has released a series of pamphlets and jingles to describe how each temperature feels.(Supplied: BOM)

To help, the weather bureau has invented a series of jingles to describe the sensation of a temperature in degrees Celsius.

These included the “frosty five”, the “tingling tens”, the “temperate twenties”, the “thirsty thirties” and the “flaming forties”.

Miles to metric measurements

The change from Fahrenheit to Celsius was the first phase in the change from nomenclature to the metric system.

At the same time, they abandoned the use of inches in atmospheric pressure.

black and white view of a map
Switching from Fahrenheit to Celsius was just one of many steps in changing to the metric system.(ABC News)

Stage 2 of the conversion, in April 1973, changed the wind speed to kilometers per hour instead of miles per hour.

And the last stage, completed in 1974, saw rainfall amounts, wave heights and snow depths changed to meters.

Mr. Bergin said this change was more memorable.

“I know the rainfall wasn’t as regular and neither was the wind,” he said.

“That’s still the case today, if you go through rural and regional areas and talk to particularly old people, the language is still very close to thumbs.

“They’ll tell you they’re 50 miles from a certain town, but we had half an inch of rain last night.”

A smiling Mike Bergin sits at the Perth BOM desk, with weather maps on computer screens in the background.
Retired meteorologist Mike Bergin was training with the BOM the year they moved from Fahrenheit.(ABC News: Hugh Sando)

Weather forecasting was not the only aspect of Australian life to switch to the metric system during this period.

Between 1970 and 1980, road speeds, clothing sizes, scales, recipes and medical prescriptions were also converted, among others.

Despite the potential for disruption of normal life, the change went surprisingly smoothly in the private and commercial spheres, according to a 1982 federal government report.

The report describes the metrication process as “the most significant event in Australia’s integration with the modernizing world”, set in motion following the changeover to decimal coinage in 1966.

A Senate committee determined that the move to metrics was both desirable and practical – simpler, more efficient, and more widely used around the world.

In 2022, only a few countries still use the Fahrenheit scale.

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