The balmy finish to August will push the capital over the line to record its highest ever average daytime winter temperature – likely to be either 14.1 or 14.2 degrees, depending on how high the mercury rises on Saturday.

While it’s more than 2 degrees above the historical average, it is only marginally hotter than winter 2011, the previous warmest, which had an average maximum temperature of 14 degrees. The average minimum temperature this winter was also well above average, at 1.8 degrees.

Bureau of Meteorology climate scientist Blair Trewin said there have only been two days so far this year which haven’t reached double-digit temperatures, which could also set a new warm-weather record for the year if that number remains unchanged.

“The biggest driver we’ve had this winter is we’ve had a real lack of southerly and south-westerly cold outbreaks, and those are what usually push the coldest air into south eastern Australia,” Mr Trewin said.

Mr Trewin said the winter weather wasn’t directly linked to the hottest summer on record just passed, but said it did fit into a long-term warming trend.

It was also slightly wetter than average, helped by higher June rainfall, and by the overnight thunderstorms on Thursday. It’s the wettest winter since 2005, after a run of relatively dry winters in the capital.

Mr Trewin described the outlook for spring as “bland” for the Canberra region, with a good chance temperatures would be generally close to average, and a slight chance rainfall might exceed the average.

But with current forecasts predicting the run of warm days will extend into September, Mr Trewin said it could possibly be a record-breaking start to the new season.

“It does look like the warmth is going to ramp up in the early part of next week from Sunday onwards,” Mr Trewin said. “There’s a realistic possibility of us having the earliest ever day over 25 degrees [in September].”

As if on cue, the Bureau of Meteorology has forecast a mostly-sunny Saturday for its Centenary celebrations at the Shine Dome in Acton. The event will go from 9am until 3pm, with regular talks from forecasters and climate scientists on the history of Canberra’s weather over the past 100 years.

There will also be hands-on activities aimed at children, including tracking the day’s weather with two weather balloon launches, and using barometers, cup anemometers, whirling psychrometers, and a host of other meteorological gadgets.