One month’s worth of rainfall is expected to be dumped on Melbourne over two days, as unseasonably warm weather plummets to a “blast of winter”.

Forecaster Graeme Britton said Weatherzone was predicting between 30 and 60mm to fall on Thursday and Friday – close to an average monthly total of 56mm.

The Bureau of Meteorology warned Friday rainfall could even be as much as 80mm.

Melbourne’s north-east and bayside areas are expected to be hit with some of the heaviest rainfall, most of which will fall on Friday.

The maximum temperature is expected to be a cool 13 degrees for both Thursday and Friday, the coldest maximum temperature since September 2017.

Hail could make an appearance, and strong wind gusts are expected to make the cold snap feel even chillier.

“There will be quite a gusty wind to go with this system … which will make it feel a few degrees colder than the actual temperature, given the wind,” Mr Britton told The New Daily.

Southeastern Australia is in for a cold snap later this week, with the potential for heavy rain from Thursday/Friday. Here are three scenarios (different models) for where that rain could fall. Check https://t.co/4W35o8i7wJ regularly for updated forecasts and warnings. pic.twitter.com/llFou32UOF

— Bureau of Meteorology, Australia (@BOM_au) May 8, 2018

The gusts could reach about 80km/h in coastal Melbourne areas on Thursday, and peak at up to 90 or 100km/h on Friday.

Wind gusts and colder than average temperatures will continue through the weekend, but the worst is expected to come on Friday.

Eastern parts of the state will be worst hit by wind and rain, which could exceed 80mm over the two-day period.

Mr Britton said alpine areas could get more than 100mm, while the BoM said snow could also be dumped in the region.

The BoM put a warning out for sheep graziers in the Mallee, Wimmera, Northern Country, North Central, North East, South West, Central, West and South Gippsland and East Gippsland districts.

“Sheep graziers are warned that cold temperatures, showers, isolated thunderstorms, small hail and westerly winds are expected during Thursday,” the warning said.

“All districts are likely to be affected. There is a risk of losses of lambs and sheep exposed to these conditions.”

The rain comes after an extended dry spell for Melbourne. Just 16mm fell in April, well below the 57mm average. March received 20mm rain, while just 1.6mm fell in February compared to the 48mm average.

“It’s been a very dry few months for Melbourne, and Victoria as well,” Mr Britton said.

Despite the stark drop in temperatures, the forecaster said the cold snap won’t necessarily move straight into winter.

“This is a significant change to the warm trend we’ve seen over the past few weeks, but it’s not to say we won’t return to temperatures in the low 20s later in the month.”