Tennis fans everywhere will know that we had a pretty torrid heat wave last week, the first week of the Australian Open. It wasn't our hottest, but it went for four days. In Melbourne max temperatures were were 42.8,41.7, 43.9 and 43.9°C, or, if you prefer,109, 107, 111, 111°F. This forecast from the BoM explains what was happening; it happened as predicted, a bit warmer at the end. MikeH in comments noted this more complete report from B0M.
There's the usual argument about AGW. WUWT doesn't think so. In fact, they won't much concede that it was hot, and say it happens all the time here. So I thought I'd review in this post our summer temperature history, and also refute some notions that it's all happened before but been hushed up by "adjustments".
Monkey Mia, WA, From ABC
The Bureau of Meteorology here has online daily data which is unadjusted. It's convenient to use, but not to download. For that I used GHCN Daily files which can be found here. They are unadjusted historic temperatures, derived from (and apparently identical to) BoM. Melbourne’s file is ASN00086071.dly; it has good coverage from June 1855 to Dec 2013. I supplemented it with current online data to date.. I extracted them to a CSV file which I've placed here.
I've plotted each summer (DJF) max temperatures from 1856 to 2014 (counting by the JF year).
You can switch from year to year using the top buttons, and go to any decade year with the radio buttons.
Our summers are made up of many pleasant days, with southerly winds, with heat when the wind blows from the North. Notably hot summers were in 1908, 1939, 1983, 2009. The last three had devastating wildfires on the hottest days, which I've linked. Big heat has bad consequences here. We lose towns, homes and people.
Table of extreme temperaturesOriginally, I had here a list of the twenty hottest days in Melbourne since 1855. Following a suggestion in comments by SC M, I have updated to inclide tables of the 20 highest daily max, highest min, lowest max and lowest min. I've marked those occurring in the last five years in red. For highest max, there are seven. Click the buttons.
High Max Low Max High Min Low Min
Adjustments?In the WUWT thread I encountered over and over claims that BoM had rigged the records by adjusting old readings downwards. It's very hard to get specifics (typically the complainant just gives a link, which is often to a rant about GHCN, or GISS). Eventually it crystallised to complaints about Acorn. This is a recent homogenised set of data for 112 chosen stations, starting in 1910. The lead post in fact claimed that the BoM had discarded all data before 1910, which puzzled me.
But of course the data is not discarded. All the old unadjusted data is available from BoM, and also from GHCN. And it is what the BoM uses when talking about station extreme temperatures. If you go to the Melbourne climate page, for example, it will tell you that the hottest December day was 15 December 1876. That's not Acorn.
So how do we know these are really unadjusted? I've known since boyhood that Melb reached 114.1°F on Jan 13, 1939. That's what the record still says. But I checked others. The National Library has an old Melb (and others) newspapers here. I've checked a few of the reportewd high temps; the GHCN record linked here agrees with the contemporary reports. I think it's up to claimants of adjustment to give one example from this dataset.