Southeast Queensland’s Driest January on Record & Hottest January in Decades

The extraordinary summer of 2018-19 continues as records tumbled across Southeast Queensland.  Many locations recorded their driest January on record which combined with high temperatures resulted in significant bushfire dangers on several days – which for what is traditionally one of the wettest months of the year is quite rare.  Brisbane AP, the Gold Coast, Sunshine Coast, Toowoomba, Dalby and Gatton all recorded their driest January’s on record.  Meanwhile Brisbane CBD had an average maximum of 31.9C making it the hottest January since 1903 (though the station was closed in the late 80s through into the 1990s).

One of the most significant statistics was the Sunshine Coast AP, which not only had its driest January on record, but its second driest month of record!  This is significant because winter is traditionally the dry season for Southeast Queensland, so for January to be drier than most of the months in the dry season is quite extraordinary and only goes to reinforce how unusual January’s weather patterns have been.  To top this off, northern Queensland ended January with significant flooding thanks to a deep monsoon low and trough – and that pattern is likely to continue until at least early next week.

One aspect that made the situation so unusual was that the record dry and high temperatures occurred with predominantly easterly winds occurring on each day!  However these easterly winds lacked two aspects which resulted in conditions tending so dry.  The first was a large blocking high in the Tasman Sea.  This prevented any weather systems from sweeping in from the west (that might help lift any moisture from the easterly winds).  Second is that air was wrapping around a high pressure, hot dry air was wrapping down the southern side of the low – pushing over New Zealand (and helping to produce record heat in New Zealand also).  This air then got pushed into the southern Coral Sea where it diluted the traditionally humid, easterly winds resulting in a lack of traditional coastal showers that normally occur.

One of the reasons for the blocking high was the intense (and also record breaking) heat across central to southern Australia.  The air was so hot that it was constantly rising and generating low pressure over the interior of the country.  Since high pressure systems contain sinking air, these systems tend to favour cooler areas and in Australia’s case, that means the surrounding oceans.  As such the heat across central Australia helped to reinforce the blocking high in the Tasman.

If we compare the synoptic pattern of January 2019 to the average January synoptic pattern from 1948 to 2018, we can see some significant differences.  Firstly the heat trough across Australia is nowhere as pronounced or deep, and mostly located across northern Australia (where it normally sits).

Secondly, we see a much weaker ridge and high over the Tasman Sea and much longer easterly fetch of winds coming off the Pacific Ocean which would traditionally produce much more moisture (helping to at least produce coastal showers).

The result for January 2019 was a very dry and hot January for not only Southeast Queensland but also northeast NSW (where many locations also had their driest January on record).  For a full list of records and statistics, see below.