Records tumble in our hottest January

The ACT sweltered through its hottest January since records began in 1939, punctuated by a series of severe thunderstorms that brought damaging winds and hail, but only near-average rainfall.

It was a month full of records, with Canberra Airport recording five days above 40°C, a record for any month and the calendar year, with an unprecedented four of them in a row from 15 to 18 January.

Canberra Airport’s mean maximum temperature was a record 34.5°C, 6.3°C above average and 1.7°C above the previous mark set in 2017. The mean maximum was also a January high in Tuggeranong at 34.1°C, beating its previous record by just over 2 degrees.

The heat was unrelenting thanks to a series of heat waves as a high-pressure system in the Tasman Sea blocked the progress of cold fronts, drawing down hot air masses from northern Australia. Canberra experienced 19 days higher than 35°C, just over six times the January average. The annual record is 25, so the ACT is well on the way to another record there.

While the January high at Canberra Airport fell short of the 1968 record of 42.2°C with a maximum of 41.6°C on the 16th, Tuggeranong did crack it with 40.8°C the next day.

There was little of the usual overnight relief for Canberrans, with both the Airport and Tuggeranong breaking records for minimum temperatures with 17.7°C and 18.0°C respectively, beating their previous records by 1 to 1.5 degrees.

There were eight nights above 20°C, a record for any month and twice the previous marks of four in January 1939 and January and February 1973. Already this year the number, of 20°C plus nights is equal to the annual record from 1973.

The minimum temperature did not drop below 15°C on 25 days at Canberra Airport, surpassing the record of 23 days set at the closed Airport site in January 2006.

Most of the ACT’s rainfall was dumped in thunderstorms, with Canberra Airport receiving 61.2mm, just above the long-term average of 58.0mm, and delivered on 11 days, above the average of seven days.

Canberra Airport recorded a wind gust of 83 km/h on 8 January when thunderstorms downed trees and caused power outages, and hail up to golf-ball size peppered the capital on the 11th.

While February has started with a cool change, the weather bureau’s outlook remains for warmer-than-average temperatures over the next three months, with average rainfall.

Bureau senior climatologist Dr Andrew Watkins said the heat through January across Australia was unprecedented.

“We saw heatwave conditions affect large parts of the country through most of the month, with records broken for both duration and also individual daily extremes,” Dr Watkins said.

“The warming trend which has seen Australian temperatures increase by more than 1 degree in the last 100 years also contributed to the unusually warm conditions.”