Melbourne, Adelaide and Hobart are all set to start May with maximums in the mid-to-high twenties that are around 10 degrees above the monthly average.

All three cities – along with much of southeastern Australia – have experienced an unseasonable run of warmth in recent weeks, as high pressure systems centred over waters south of the mainland have blocked cold fronts from pushing northwards.

That pattern looks set to continue for at least another four days in all three cities, before a slow-moving cold front starts to disturb the stable set-up during the weekend.

Let’s take a quick look at Friday’s weather in each city:

Melbourne

Melbourne is having an exceptionally warm end to April, with maximums exceeding the monthly average of 20.2°C on 10 of the last 11 days of the month – and by three degrees or more on each day.

But this week’s warmest day could be Friday, May 1, when the forecast maximum of 26°C would be nearly 10 degrees above the monthly average of 16.8°C.

Adelaide

Like Melbourne, the South Australian capital has had a very warm run recently. Since April 18, maximums have been well above average on every day except one, and that trend will continue until the end of the month this Thursday.

Indeed, the five day period leading up to Anzac Day was Adelaide's warmest spell this late in the season in 105 years. 

On Friday, Adelaide is expecting a maximum of 29°C. That would be more than 10 degrees above the average May maximum of 18.6°C. 

Hobart

Image: Parts of SW Tasmania will even experience heatwave conditions, bearing in mind that the BoM defines a heatwave as a prolonged spell of unusually warm day and night-time temperatures for the time of year at particular locations relative to recent weather, rather than extremes above a certain threshold like 40°C. Source: Weatherzone.

Earlier this month, the Tasmanian capital shivered through a day which peaked at just 11.5°C as snow coated kunanyi/Mt Wellington. 

A high of 25°C is on the cards for this Friday, which would be more than 10 degrees above the average May maximum of 14.6°C.

What’s causing the unseasonable warmth over southeastern Australia?

Image: Synoptic chart for Friday, May 1, 2026. Source: Weatherzone.

As mentioned at the top of this story, high pressure systems have been blocking the cool, showery weather systems that lurk in the Southern Ocean.

Friday looks to be the warmest day of the week across the southeast as air circulating anti-clockwise around the high centred near New Zealand drags warm air from the interior of Australia southwards.

By Sunday and Monday, cooler, unstable weather should hit the southeast as the blocking high drifts east and the cold front pushes through. There’s also potential for a much colder outbreak around the middle of next week.