No increase in hot days at Bathurst

WHEN a cause is incorrectly attributed to a misfortune, we forgo the opportunity to learn, we forgo the chance to plan so that we can avoid making the same mistakes into the future. In the wake of the February 2009 Victorian bushfires, a book by Roger Franklin, Inferno, The Day Victoria Burned, explains that we are losing ground when it comes to managing fire [1]. This may have a lot to do with willfully ignoring the well-documented mistakes of the past, in favor of popular politics.

The cost of continuing to ignore the evidence is enormous, not just the loss of human life – 173 people died in Victoria on February 7, 2009 – but the bush could be so much healthier, and safer for native animals. Watercourses would be protected from erosion so common immediately after ferocious fires, and also from the regrowth that has significantly reduced water runoff into the Murray Darling.

Instead of implementing the well-documented solution of prescribed burning [2,3], as a community we are distracted with commentary about a ‘clear link’ between climate change and bushfires [4].  Such commentary often ends with the recommendation that we need to invest much more as a nation, not in prescribed burning, but in ‘climate change’.  This entire discussion is prefaced on an assumption that temperatures are actually increasing in Australia. The technical literature specifically claims that the impact of increasing carbon dioxide concentrations will be manifested through an increase in maximum temperatures [5].

This last week bushfires have been raging in the Blue Mountains. Just to the west of the Blue Mountains is the town of Bathurst. Bathurst has one of the longest temperature records of any locality in Australia, with daily maximum and minimum temperature measurements recorded at the jail from 1858, and from the agricultural research station since 1909 [6].  This temperature record shows that contrary to popular perceptions, it has not been getting hotter at Bathurst.

If we consider the longest temperature record, which is the daily mean maximum temperatures for Bathurst jail from 1858 to 1983, the hottest day was January 12, 1878, see Chart 1. On that day, 135 years ago, a mean maximum temperature of 44.7 degree C was recorded.

There are no temperature recordings for the jail after 1983, but recording started at Bathurst airport in 1990. The airport data indicates that the hottest day during recent times was on February 15, 2004 with a mean maximum of 40.7 degree C, see Chart 2.

The Bureau of Meteorology uses the data as recorded at the Bathurst Agricultural Research Station since 1909 for its Acorn-Sat program. This is a program where data is ‘adjusted’ and ‘homogenized’ and then particular localities are chosen in the development of an average temperature for the entire Australian continent. Such an average value, while practically useless, has political interest, and is used, for example, to develop temperature trends for Intergovernmental Panel on Climate Change (IPCC) reports.

The adjusted and homogenized data for Bathurst indicates that the hottest days on record are January 11, 1939, followed by January 14, 1939 at 40.7 and 40.6 degree C, respectively. January 12, 2013 was also hot, with a mean maximum of 40.2 degree C recorded at the Research Station, see Chart 3.


In summary, even using the adjusted and official data for Bathurst, Chart 3, temperatures are not exceptionally or unusually hot now. If we consider the longer record and the ‘unadjusted’ data, it was much hotter in the late 1870s and then again in late 1930s than it is now, Charts 1 and 2.  This is consistent with what we know about natural climate cycles [7].

It is fashionable to make a link between global warming and the recent bushfires in the Blue Mountains. But such claims of a causal connection are not supported by the available evidence. In particular, if the technical literature specifically claims that the impact of increasing carbon dioxide concentrations will be manifested through an increase in maximum temperatures, but there has been no increase in the maximum temperature, then the theory, in the end, is nothing more than a myth.

Public policy is best based on evidence and logic, not popular politics, however emotionally engaging and personally compelling. Indeed, blaming the bushfires on global warming won’t save one home or one watercourse from catastrophe.

Bushfires cannot be entirely prevented, but periodic mild, patchy fires alleviate the build-up of heavy fuels, so that when a fire does start it is easier and safer to suppress and does less damage. A regime of prescribed burning also produces a healthier and more vigorous forest and is better for biodiversity.

PS. It has been suggested that writing articles like this, and presenting evidence by way of the above charts, is akin to pouring a single bottle of water on a fire dance of raging global warming alarmists. Perhaps, but help me increase the humidity a little, by sharing this article with your friends and colleagues… its not exactly patch burning but it can perhaps help reduce connectivity through sowing a little healthy scepticism.



1. Inferno, The Day Victoria Burned by Roger Franklin. Slattery Media Group, 2009. Pp.267

2. Living with Fire in NSW National Parks: A Strategy for Managing Bushfires in National Parks and Reserves 2012-2021, by NSW Office of Environment & Heritage,

3. Bushfire Management in Australian Forests by Roger Underwood.

4. Scientists say climate change link to bushfires demands action. Australian Broadcasting Corporation. 21/10/2103, Reporter Tracy Bowden.

5. The Sensitivity of Australian Fire Danger to Climate Change by Allyson Williams, David Karoly and Nigel Tapper. Climate Change, volume 49, pages 171-191.

6. Unadjusted temperature data is available from the Bureau of Meteorology at . ‘Improved’ data is also available from the Bureau and is labelled ‘High Quality’ or ‘Alcorn-Sat’ at .

7. Taxing Air: Facts and Fallacies about Climate Change by Bob Carter. Kelpie Press, 2009.

And if you would like to read more about patch burning, Nyoongars, Noolbengers and more click across to…

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22 Responses to “No increase in hot days at Bathurst”

  1. Jennifer Marohasy

    A Bathurst anecdote from Robert…
    “Strong hot winds, clouds of dust, and a thick hazy atmosphere continue to be the prevailing characteristic of the weather in the district of Bathurst. On Saturday and Sunday last, the smoke from the enormous bushfires raging around us in every direction, hung over the plains like a huge fog, exceedingly oppressive and totally concealing from view the surrounding mountains.”
    The Bathurst times. 19 October 1865

  2. Robert

    Rainfall would also be interesting, Jen. I know that in my region the driest times were mostly way back in the record. (Sydney’s, of course, was 1888, though I’d hate to think how dry it was in the early 1790s.)

    I recently had to explain to some o/s people that the MDB has been wetter since the long half century of rain deficit to 1950. It’s very odd how educated people (especially) just assume the opposite. Or maybe it’s not so odd.

    Anyway, great job on Bathurst!

  3. Peter (professional forester)

    Good point.
    The fire triangle, which is drummed into forestry students at University and Technical courses. There are three essentials to sustain a fire: ignition, fuel, oxygen – without any one of these three there is no fire. Climate is not part of the fire triangle. Climate only influences fire behaviour once the fire has started and it could influence fuel conditions if there is time for fuel to build up (and either dry out or get wet).

    There is no cause and effect between climate and fire. I’ve experienced plenty of extreme fire weather days, but as no fires were ignited, there was no fire. I’m yet to experience spontaneous combustion caused by hot weather!

    • Robert

      Peter, in my part of NSW we try to burn off in winter, and don’t necessarily wait for the end of August, which can be lethally windy.

      I don’t understand how anyone can regard October as early for a major burn in NSW – or how they can claim greater intensity for modern fires. For intensity, look at conditions not modernity or time of year. The awesome Peshtigo in 1871 occurred concurrently with others (incuding Great Chicago) around the Great Lakes in mid-autumn. The world’s biggest known inferno was, indeed, a summer fire…but in Victoria 1851.

      Every time something goes wrong we are treated to “analysis” to show the exceptionalism of recent events and climate. This would be an okay proceeding if the same people went looking for evidence of past events. In fact, they never want to look too hard at all. They might find an event in 1895 or 1951 which does not fit their exceptionalist script.

      Anyway, great to hear from a forester. We now have more forests on the midcoast…but I’ve forgotten what a forester looks like.

  4. George Montgomery

    So you’re saying that, if global warming is occurring, it has no effect on bushfires i.e. the extra heat drying out the ground and, indirectly, the trees and undergrowth doesn’t make the bushfire more intense.
    Am I hearing you say that the increased overnight temperatures, associated with global warming, doesn’t have an impact on the intensity of the bushfire i.e. there is a lull in the bushfire overnight, which doesn’t seem to be happening with the current NSW bushfires (and those earlier this year in the USA and Russia).
    And based on your assertions, are you saying that there’s no link between the earlier starts to the bushfire season and global warming.
    Perhaps you’ve mistakenly interpreted the literature as saying that global warming causes bushfires. No climatologist has ever made that claim. I think that can be labelled a strawman argument i.e. making a false statement and attributing it to someone or something. Climatologists have always claimed that global warming would cause bushfires to be more intense which is what we’re seeing.
    As to Jennifer’s claim that global warming is not occurring based on the temperature records in one nanoscale fraction of the globe, Bathurst, that’s just plain ridiculous. But if we accept that this Bathurst-temperatures line of thinking is correct, how does that explain away the earlier starts to the spring flowering season, the increase in minimum overnight temperatures, …

    • Anne Marie

      Very well said, people who believe in climate change are always presumed to be alarmists

    • andy

      “As to Jennifer’s claim that global warming is not occurring based on the temperature records in one nanoscale fraction of the globe, Bathurst, that’s just plain ridiculous” – strawman strikes again.

  5. Barry

    George, I thought it was abundantly clear that the author contends Bathurst is not experiencing unusual or unpredented high temperatures. This undoubtedly means that “global warming” (presumably the average temperature increase which occurred during 1976-96) is not currently affecting the temperatures being recorded in Bathurst.

    It seems equally obvious that bushfire intensity or earlier seasons could not be caused by warming elsewhere on earth, if that warming is not being reflected in local Bathurst temperatures.

    You appear to have strong objections to instrumental temperature records, each of which measures “one nanoscale fraction of the globe”. Is it your preference to rely upon computerised simulations?

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  7. halfacow

    Why have you chosen 35C? Why have you not considered variation from minimum temperatures?

  8. Jennifer Marohasy

    Hi Halfacow, The Climate Commissioners tend to use the very arbitrary value of 35C in their reports as designating ‘hot days’. As I was exploring the data, I also used this value of 35 as an arbitrary lower limit, and found it worked to show the hotter day trends.
    Not included in this blog post or presented anywhere publicly, but out of curiosity, I’ve also plotted minimum data… both daily and also monthly values. Which are you most interested in (daily or monthly) and what would you consider a good cut off i.e. what value might designate a colder day? Alternatively I can plot all the minimum values. Let me know and I will do another blog post with this information. I’ve spent a lot of time with the data, and have too many charts too show all at once. Cheers,

  9. ghl

    Thank you for this effort, I appreciate it.
    One query, in the term “mean maximum”, should “mean” be omitted, I find it confusing.

    • Jennifer Marohasy

      Hi ghl, I’ve just now reposted the charts after removing the word ‘mean’ from the titles of charts 1 and 2. Much thanks for your interest and attention to detail.

  10. Jennifer Marohasy

    ghl, Mean can be omitted from the daily values. I initially plotted monthly mean maximum, but what are shown in these charts are daily plots where maximum temps exceed 35C. I’ve got a few things to do this afternoon. But will fix the charts this evening/tomorrow morning and repost. Thanks.

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  12. Graham

    Hi Jennifer, can you do a plot of days in October over 35? Part of the argument appears to be that it is early in the summer for these fires.

  13. Graeme M

    Hi Jen, I’d be interested in the plot of all lowest maximums, that is, days when max temp is BELOW 35C.

  14. anitah

    On the question of the fires in October; I think the answer lies in the notion that October is the craziest month of all for variations in weather/fire hazards etc.. The idea of four seasons doesn’t really fit here. Maybe even Oct. being the 5th season idea as used by indigenous knowledge AFAIK.

    The other thing about major fires in October is that the load is not so dry and so it is actually a good time to burn slower cooler fires. These areas ought to be able to get on top of Summer fires IMV.

    • Jennifer Marohasy

      Hey Anitah, Thanks for your comment. And I was sent an email from Art Raiche with the following advice:
      “It is well known, or at least it used to be well known, that the urban homicide rate in US cities peaked during hot summer nights. These homicides were due to guns. What started the most serious fire in the Blue Mountains? Guns, in this case not urban blacks but Australian soldiers shooting guns, almost surely because it was too hot. There you have it. Hot weather causes men to shoot guns and the more hot days we have the more they will shoot and some of these shootings will start fires. It is so obvious.” 😉

  15. John Nicol

    Excellent article Jennifer. This needs to be spread far and wide. It really does show up the total dishonesty level to which people like Steffen and Flannery are prepared to stoop to gain traction in the debate without the remotest respect for any science whatsoever. Well done and best wishes.
    Kindest regards


  16. Jennifer Marohasy

    I was sent this link to prove that it’s getting hotter at Bathurst… . Seriously!
    Obviously if one is very selective, and, for example, begins plotting data from the lowest point in a series it would appear that it was getting hotter at Bathurst. But of course, its dishonest to start a data series at a low point, when data for the same site extends back much further and when the full series is used its obvious that the 1960s represented a relatively cool patch in a cycle. However, interestingly this was exactly what the famous Stern Report published for the British government did with respect to various parameters including rainfall. More recently its been a trick that the Climate Commission has used.

  17. Jennifer Marohasy

    This article was republished at On Line Opinion

    I’m just reposting the following comment that followed the article at OLO, here, for future reference: Garry in Liffey – it’s all well and good to declare hottest this and record that when you don’t actually reveal your data source.
    For example, in the BOM Hottest September Media Release they state what sites were used in creating the report.
    So I checked on the first one on the list – Halls Creek. They claim 40.2C this September was a new record for Halls Creek.
    Yet if you go to the BoM data online site and call up Halls Creek you will find that there is a closed station, Old Halls Creek, and if you check that record you will find that the highest temperature recorded in that data base was 12th September 1917 with a reading of 40.2C

    This is the problem we face with this current BoM. They have closed down many of the sites that have long periods of consistent data, Casino, Central Lismore, to name a couple, and have removed the data from the national data base. What we have today in the ACORN data set is an homogenized, adjusted temperature record with the predominant adjustments to a warmer present and a cooler past.

    Jennifer’s analysis of Bathurst temperatures is a perfectly adequate method of seeing if a warming planet is in part responsible for the intensity of the recent fires. We know that globally the planet has not warmed for the past 15 years but maybe the area around the bush fire may be warming unnaturally. Yes the maximum temperatures in Bathurst from the 60s to the 2002 have risen slightly but over the past 10 years it has in fact cooled slightly.

    MacQuarie University created a paper for the Senate Standing Committee on Environment & Communications Inquiry into Recent Trends in and Preparedness for Extreme Weather Events.

    They concluded that:

    Research into the economic impacts from natural disasters now spans many parts of the world. No study has yet been able to detect an anthropogenic climate change influence. Anyone asserting the contrary now has a mountain of peer-reviewed literature to climb over.

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