Original data from
60 of the oldest
weather stations
across Australia:
The Bureau
of Meteorology
BoM) defines
a very hot day
as having
a maximum
temperature
of 40C
or greater.
The 60 longest running
ACORN weather sites,
all open in 1910,
show raw temperature
data had just as many
“very hot days” in the
World War I era
as they do now.
That's still true,
but the numbers
have been "adjusted"
and no longer
say that.
Until BoM "adjusted"
temperature data
twice, since 2010
( ACORN 1 and ACORN 2 )
The main change
was decreasing
the frequency
of 40C+ days
in the early 1900s.
Cooling the past
causes a higher rate
of global warming.
In 2011,
the BoM’s
ACORN 1
"adjustments"
made some
very hot days
in the
early 1900s
"disappear".
In 2017,
the BOM's
ACORN 2
"adjustments"
significantly
decreased
very hot days
versus ACORN 1,
mostly by
decreasing
40C+ days
in the first half
of the 1900s.
The 60 sites
with long records
are the most useful,
even though many
of the weather
stations have moved
from post offices
to airports, and
later got new
fast reacting
electronic
"thermometers"
that could capture
momentary heat
peaks that old glass
thermometers could not.
Note:
The charts below
are slowly moving
gif charts:
Note:
The charts below
are slowly moving
gif charts:
