Canberra records coldest September night in 74 years – since 1939

Quite a morning for the 1st of September – and the 2nd is also frosty with the 30 minute data from the Airport shows a minus 4.8 at 6am.
Even Toytown had a chilly morning Saturday.
But a couple of things the main stream media do not rush to tell you.
Australian mean temperature has been cool for at least a year.

And ditto Australian nights – and note that this map shows clearly the error in BoM gridded data that I jokingly named “national night-time hotspot”.

Just Google – national night-time hotspot – to find my June 2011 article birthing the NNTHS and others of mine commenting on the BoM gross error.
And of course the data from Sydney region and Canberra Airport is in the face of the ever expanding urban heat island which is inexorably driving up temperatures.

22 thoughts on “Canberra records coldest September night in 74 years – since 1939”

  1. Overnight minimum temperature for Canberra (i.e. morning 2/9) reported in Adelaide as -7. Forecast for overnight minimum this morning was -3. Global warming is so quick!

  2. That hotspot on the WA/NT border is from the Giles weather station, which has a full time staff of 4 meteorologists. If full time meteorologists can’t get measuring temperatures right, what does that say about the quality of the data from elsewhere?

    Pics of the station on Google images, but I couldn’t find one of the stevenson screen.

  3. I’d add that between Giles and the coast there appears only one station located at Newman Airport. With the iron ore boom, traffic will have increased by a very large amount as will the size of Newman itself.

    The airport website reports the following,

    Expanded jet parking bays, and a new taxiway linking to the main runway;
    Upgrading of the runway surface and existing apron and taxiway;
    Construction of a new terminal building;

  4. Warwick and Philip, here is the BoM page on Giles:

    Many photos. It would be a curious to see what could be learned by placing a few dataloggers at distance from the station at 2M heights at increasing distances from the station. While the Tmin effect seems so large compared to the facility itself, it is possible that the buildings and radar disrupt the boundary layer in nighttime prevailing wind by causing turbulent mixing, and thus a warming. Given there’s nothing else around for hundreds of kilometers except scrub bushes, this might be what is going on.

    See McNider et al 2012

    A check of wind directions against the Tmin anomaly might help confirm this.

  5. Sorry Philip and Anthony I have been busy – should have got to this quicker – the station causing the “national night-time hotspot” is Walungurru – Number:15664 just inside the NT – I have a map here and the original story from June 2011. Giles is just in WA and is to the SSW – and the frequent night-time anomalously warm numbers from Walungurru induce a contouring aberration which usually affects Giles because being a neighbour. How the BoM fails to notice this – which you might think would lead them to correct their gridded data – I fail to understand.

  6. The mentioned dates, 1st and 2nd September 1939 are remarkable, and it seems to far fetched to link the low Canberra temperatures to any event in the northern hemisphere

    ____ There was a serious flood in Northern China in July 1939; death-toll between 200,000 and 500,000 [. Water in the streets of Tianjin (120 km south-east of Beijing) was two meters deep, so that boats were the only
    _____ Only ten days before WWII started, on August 20, 1939 , the Red Army with 100,000 troops went into combat with the Japanese Army comprised of 70,000 soldiers (Kwantung Army) at Nomonham, a place on the boarder between Outer Mongolia and Manchuku, in fine weather (NYT, Sept. 17, 1939). The Soviet forces had brought with them more than 400 tanks, 200 heavy guns, 400 armored cars, 500-700 airplanes and several thousand tons of ammunition, shells and bombs to the Far East , over a distance of 3,000 kilometers. Presumably not less military equipment will have been available for the Kwantung Army, which eventually was the loser in this event with 20,000 men dead, when truce was signed on September 16. More at :

    ____In September 1939 the USA sun state California had to cope with a number of weather caprioles. The unanswered question until today is what role an El Niño event had in that place at that time, and the contribution of war activities in China and Europe, due to the excessive release of condensation nuclei. Much too extraordinary and seldom was the situation that caused high precipitation during September with 370% above normal in California (Alabama, 119%; Arizona, 335%; Nevada 327%; Utah 261%); see

    ___There is nothing significant in the central Pacific. For the global temperature situation in autumn 1939 (Sept/Oct/Nov), see:

    Ed note: Interesting history ArndB – I have often wondered if WWII history would have been changed if the Japanese had used their large land army in Manchuria in mid-late 1941 to make a thrust west along the Trans Siberian. But they never did.

  7. I think this is a good candidate for the Walungurru BoM station – put these into Google Earth

    -23.272786° 129.384687°

    The fenced in enclosure looks right, the objects in the enclosure match size/shape I would expect for a Stevenson Screen and rain gauge.

  8. The other possibility is at the airstrip

    -23.265557° 129.384336°

    The fenced enclosure also fits the expectations. Given this station provides 30 minute automated readings, I’d vote for the airstrip over my first choice in the comment above.

    If it is at the airstrip, note that we have a large area that is red clay dirt for the airstrip, and the grasses/shrubs are absent. That may explain the anomaly. My bet is the short history of this station points to it being installed at the airport at the request of the mail carrier. It seems a mail plane flies into Kintore airstrip every Wednesday.

    Again a good candidate for placing some dataloggers at distance to see what is going on.

  9. I see Canberra has another frost today on the 3rd Sept.
    BTW – I do not see the Walungurru “national night-time hotspot” gross BoM error as being in current data – I think it is due to the BoM selecting the WRONG Min T “normals” for Walungurru – which are built in to their gridding numbers and constantly distort the gridded contour maps.
    My amazement is not that a mistake like that can be made – but that the BoM does not see it over YEARS.

  10. @RE: ”Ed note: Interesting history ArndB – I have often wondered if WWII history would have been changed if the Japanese had used their large land army in Manchuria in mid-late 1941 to make a thrust west along the Trans Siberian. But they never did.”

    “ED” Please note: War efforts on the continents presumably did little on climate (weather) changes, but I would appreciate if the PACIFIC rim States would kindly take a serious interest what happened toward the end of WWII in the Western Pacific Ocean by the biggest naval assault on the marine environment , see : that on one side the saw the USA, UK, Netherlands, & Australia, on the other side Japan, which became significant in:
    ____winter 1944/45 ) when the biggest naval activities stretched (TM 13) as shown here:

    It is not only about the winter 19444/45, but also about the month May and July 1945, which are the coldest months since air temperature had been taken! See e.g. Aikawa & Onahama (NW & NE of Tokyo):
    Any kind attention is very welcome.

  11. Warwick,
    Just perused the BOM’s monthly summary for August in Australia. The max temp anomaly was +1.49C and the min temp anomaly was
    -0.83C. Then this statement:-

    ‘The Australian diurnal temperature range (the difference between maximum and minimum) anomaly was the highest on record for August and the third-highest on record for any month; the anomaly was 2.32 °C.’

    Surely they have made a mistake here (the mean should be about +0.33C, not +2.32C). Have I missed something?

    BOM summary here.

  12. I can not comment on their “temperature range” claim without seeing a time series going back decades.
    This landmark paper by many high priests(esses) of GW claims that globally (and over Australia) DTR has been closing. So it is interesting that the DTR is high over Australia now.
    Back to the BoM – in line 3 under Temperatures – they say “No State or Territory recorded below-average monthly maximum temperatures.” Just take a look at Victoria on the max anomaly map. It must have been a close run thing. The green cool anomaly takes up most of the State – so for the BoM claim above to be correct the large green areas must have all been just cool enough to make that contour band while the smaller off-white warmer areas must have been at the top of that range and just missing out on yellow.
    The other point worth commenting on is the Australian minimum anomaly which the BoM quotes at -0.83 degrees. Now just take a minute or two to eyeball the colour contour map – you are asked to estimate what the National min anomaly would be from that map. Using the scale – estimate how warm anomaly areas balance out against equivalent cool anomaly areas. Clearly the Nation has been cool at nights in August – but from that map would anybody have guessed a number warmer than minus 1 degree ?
    To wrap up – obviously I think their conclusions are in error to the extent that the spurious “national night-time hotspot” affects their numbers.

  13. A record DTR is interesting, because the late 20th century warming was characterized by decreasing DTR almost everywhere. Cloud cover seems to be the most important driver of DTR changes. Increasing clouds = decreasing DTR.

    Its my contention that cloud changes over that period were driven primarily by aerosols, and the so called global warming signal in the surface temperature record is really an urbanization signal (combined with a step change of unknown cause in 1976/7).

    This is a good review of DTR.

    August was a very dry month here in the West in anomaly terms, with much less cloud than normal. So a record DTR doesn’t surprise me.

  14. There was a -6.4 degree celsius recorded on 10th September 1982. Canberra Airport ID: 070014

    WSH comprehensively discussed this site in an earlier post

    This station closed in December 2010. The new Canberra Airport weather station (ID: 070351) is a few kilometres away.

    The BoM’s Blair Trewin addresses this very issue in a comment # on the Weatherzone blog

    Canberra is an interesting one because a car park was built close to the old site in 2006, lifting its minimum temperatures by about 0.5 degrees on average.

    On an annual mean basis, the site move in 2008 roughly cancelled out the impact of the car park building in 2006 (i.e. minimum temperatures at the new site are roughly comparable with those at the old site as it was pre-2006). However, the new site does seem to be more susceptible to extreme low minima, particularly in autumn and spring, than the old one was. Extreme minima can be very sensitive to subtle points of local topography, airflow etc.

    The new ACORN-SAT data set ( adjusts data for changes of this type. The adjusted value for 10 September 1982 was -7.2 (i.e. our best estimate is that if the current site had been in use on that date it would have measured -7.2). These types of adjustments are very important for climate change work but probably not so important for public information purposes, unless the change is really big.


  15. What BT says needs close examination.
    I note the BoM’s willingness to attribute a carpark at Fairbairn as the reason to shift the old Canberra AP site a few hundred metres. They completely ignore the 50 + years growth of Canberra – that presumably they think can not produce heat that might increasingly warm the winds blowing to the AP. They ignore the booming AP office building & shopping precinct developments of this century – just hundreds of metres away from the instruments – that ditto can not make air warmer and for it to waft across to affect readings.
    Sounds like Nelson at the Battle of Copenhagen all over again – he raised the telescope but put it to his blind eye.

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