Australian Extreme Temperature Trends
By Paul Homewood
The Australian Bureau of Meterology have quite a lot of useful tools on their website (take note, Met Office!)
Among them are graphs for “climate extremes”, (I think they mean “weather”, BTW!). The link is here.
Starting with temperature, we have the average number of very hot days, defined as days over 40C. (There is a full explanation of the definitions and how they are calculated here. In this case, it seems that they work on an average of all stations with sufficiently long data, across the country)
Clearly there is no increase in very hot days.
The chart below shows that the average temperature of the hottest day may have crept up a little bit in 2013, but for all other recent years, again, nothing unusual has occurred.
However, when we look at very cold days, there is a very definite reduction in the number, and average temperatures are also not as low now.
You may recall I looked at Spring temperature trends in the UK, and came to very similar conclusions – that rising average temperatures were due to there being less very cold days, rather than more, or warmer, hot days.
I have not seen any real attempt to explain this phenomenon, which is, of course, highly inconvenient for those paid to scare us about “record heat”, “parched earth” and the rest.
There is also a very noticeable drop in the length of cold spells:
There is no graph for hot spell duration, but I’ll finish with growing season length, defined as:
Annual (1st July to 30th June) count between first span of 6 or more days with daily mean temperature > 15°C and first span of 6 or more days with daily mean temperature < 15°C
As far as temperatures are concerned, all of this looks to be very good news for Aussies.
I’ll take a look at rainfall extremes shortly.