Canberra has sweltered through its hottest January on record, in a month that has also seen ferocious storms strike the capital along with impressive displays of nighttime lightning.
The city has also beaten the record for the most days above 40 degrees in a year, with five already recorded. The previous record of four days in a year was set in 1939 and equalled in
If Canberra reaches its forecast maximum of 35 on Thursday, the average maximum temperature for the month will be 34.4, 1.6 degrees higher than the old highest monthly mean.
Already, the city has recorded a new highest average minimum temperature for January, after the month's warmest overnight temperature was recorded on Thursday morning, when the temperature only dropped to 22.5 degrees.
The average overnight temperature in January was 17.68 degrees, more than 2 degrees above the previous record and 3 degrees above the long-term average.
The hot weather is set to continue on Thursday, but a cool change will shift a stagnant weather pattern that has brought very warm air down from central Australia.
"There is a front to the south of NSW and behind that front we're seeing a cool, southerly change coming through southern parts of NSW and then going up the east coast and coming into Canberra this evening," Bureau of Meteorology forecaster Rebecca Farr said.
A forecast overnight low of 12 degrees will give way to a top of 26 on Friday, before temperatures rise again into next week and low-intensity heatwave conditions return to Canberra from Saturday.
"After the cool change comes through, we're seeing another high-pressure system move over southern Australia to settle in the Tasman Sea, again prompting the heating pattern," Ms Farr said.
"The good news is that at this stage it doesn't look like we'll get such a consistent streak of hot days following this heating."
But according to the weather bureau, there is an 80 per cent chance of exceeding the median minimum and maximum temperatures in Canberra during February and March.
Bureau of Meteorology climate scientist Blair Trewin said January was the hottest month for Canberra by a large margin and a far cry from Januaries in Canberra that don't even reach 35 degrees.
"It's clearly been an extraordinary month for Canberra," he said
But tracking the number of lightning strikes was difficult because the weather bureau had only recently got that capability, he said.
"The numbers certainly sound impressive but we don't really have an historical perspective to base them in."
Liz Ritchie-Tyo, an associate professor at the UNSW Canberra school of physical, environmental and mathematical sciences, said unstable conditions in the atmosphere had led to more intense thunderstorms than the city was used to.
Professor Ritchie-Tyo said the "absolutely amazing, beautiful" displays of ground-striking lightning were unusual given 80 per cent of global lightning activity was from cloud to cloud.
The higher relative humidity on days with thunderstorms was expected when it's raining, she said.
"But some of that, at least for the thunderstorms the other night, can be linked to mid-levelish – say 5 kilometres up – moisture streaming directly from the tropics."