A burst of early spring warmth will spread across the southeast of the country this weekend, ensuring the warmest weekend in many months in the most heavily populated part of the country.

Adelaide will be the warmest of the southern capitals on the weekend, with a maximum of 25°C on Saturday and 23°C on Sunday after a likely overnight shower or two. That will make it the warmest weekend since early May.

Melbourne should reach 21°C on Saturday and, even though it will be windy with showers on Sunday, the mercury should still peak around 22°C. The last Melbourne weekend with temperatures topping 20°C was the first weekend of May.

Hobart is on a temperature see-saw at the moment. After a freezing pair of days on Wednesday and Thursday with maximums below 11°C and snow to very low levels on kunanyi/Mt Wellington, a rapid warming trend sets in, with a high of 15°C expected on Saturday and 20°C for Sunday. The last weekend day to top 20°C was back in mid-April.

Canberra should reach 20°C on Saturday and 22°C on Sunday. While the national capital had a rare 20-degree winter day on Tuesday, August 26, the last time weekend temperatures topped 20°C was in early May.

Sydney should reach 20°C on Saturday and 23°C on Sunday – the first two days of an expected five-day run of maximums in the 20s. The warmest day of that streak should be Monday with a high of 27°C expected, as the warm air affecting the other southeastern capitals over the weekend pushes east.

Image: Forecast maximums for SE Australia this Sunday, September 7, according to the ECMWF model.

Some locations in southeastern Australia could also see their first 30-degree day in many months.

Mildura, in far NW Victoria, should reach 30°C on Saturday, the warmest day since April.

Temperatures in nearby towns across the SA border like Renmark should also top 30°C (potentially on both days) for the first time since autumn.

And while we're beginning to stretch the boundaries of the (unofficial) region that might be termed "southeastern Australia", it’s worth including the forecast for the outback outpost of Oodnadatta in SA’s North East Pastoral forecast district.

The town that jointly holds the record for the hottest temperature ever recorded in Australia (50.7°C with Onslow in WA) should reach 35°C on Saturday, which would make it the hottest day since March.

If you’re planning to kick the footy around the park or backyard with dad on Sunday morning for Father’s Day, there should be reasonable weather in most locations to do so – although it's worth noting that winds will strengthen on Sunday with the chance of thunderstorms across much of Victoria, Tasmania, southeastern SA, and southern NSW.

If you’re actually attending the footy, you can expect fine but chilly conditions at the MCG tonight for the Geelong Cats vs Brisbane Lions qualifying final, with mostly fine and mild conditions for the Giants vs Hawks AFL elimination final in Sydney on Saturday afternoon, as well as for all NRL matches being played in Sydney, Brisbane and on the Gold Coast.

If you’re attending the Fremantle Dockers vs Gold Coast Suns elimination final at Optus Stadium in Perth on Saturday evening and hoping for clear skies, cross your fingers and cross them hard. Our somewhat soggy Perth forecast is here.