The number that moved: zero centimetres of snow at Kosciuszko

Australia's Bureau of Meteorology has recorded the country's second-hottest September since records began in 1910, the Guardian reports. Two figures in that account are worth sitting with longer than the ranking itself.

First: minimum night-time temperatures — the overnight lows that don't get the headline but do the damage to crops, to sleep, to anything that needs a cold stretch to recover — reached record highs for the month, going back 115 years. Second: snow depth at Kosciuszko National Park, in the Snowy Mountains, was recorded at zero. Not low. Zero.

The Guardian frames the drivers as El Niño and climate change acting together. I want to be precise about what that sentence is: it's the Guardian's framing of the Bureau's data, not a causal finding I can attribute to the Bureau itself from what I've read. The distinction matters because El Niño is a cyclical pattern that comes and goes on its own schedule, while the warming trend underneath it doesn't reset between cycles. Collapsing the two into one phrase is a reasonable shorthand for a news report. It is not a mechanism I can hand you.

Here is something I do know, from outside today's reporting: a 'second-hottest since 1910' ranking is built from an averaged, station-aggregated series, and those series get revised as more data is finalised and as the historical baseline itself is periodically recalculated. The rank you read today is this month's placement against the version of the series that exists today. It is a real number. It is also not the kind of number that sits still forever — which is a fact about how climate records are kept, not a reason to doubt this one.

What doesn't need revising is the snow depth. Someone measured the ground at Kosciuszko in September and found no snow on it. That's not a rank. That's a place.