Rain across firegrounds in south-eastern Australia has slowed several blazes, but failed to provide the knockout blow authorities had hoped for.

Key points: Some firegrounds received significant rainfall

Some firegrounds received significant rainfall NSW's Rural Fire Service says about 20 blazes remain uncontained

NSW's Rural Fire Service says about 20 blazes remain uncontained Downpours in Victoria meant the number of out-of-control fires dropped from 16 to 13

Light to moderate falls over the past week have helped firefighters, however the NSW Rural Fire Service (RFS) said more than 60 blazes were still burning.

A third of those fires remain uncontained, and the showers have also hindered backburning efforts.

At least 1,000 firefighters are working on containment lines in preparation for hotter weather later this week.

"In some places it does unfortunately hold us back from doing this very important containment work," RFS spokesperson Angela Burford said.

"But in some places where we have had heavier rainfall, it's been very beneficial, and we've been able to finally put some fires out."

Most of the wet weather has been north of Sydney, with the far north coast topping the state's rainfall, with an average of 200 — 300 millimetres falling.

But further south, about 15 to 25 millimetres has been recorded around the Illawarra and Shoalhaven region, while parts of the far South Coast and Southern Ranges have only seen up to 5mm.

"In certain parts of the state, especially towards the south and south-east coast, we didn't get widespread totals ... falling directly on the fire grounds," Bureau of Meteorology forecaster Abrar Shabren said.

More rain would be welcome on fire grounds after they got a sprinkling last week. ( Supplied: CFA )

In Victoria, the number of out-of-control bushfires dropped from 16 to 13 after a downpour earlier this week.

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Melbourne was saturated with a month's worth of rain in less than 24 hours on Sunday afternoon, and severe thunderstorms led to flash flooding in parts of the city.

Bureau of Meteorology (BOM) forecaster Matt Michael said between 25 and 139 millimetres of rain fell on fire-affected areas in Victoria.

The heaviest falls were recorded in Mount Moornapa, west of Bairnsdale, with 139mm, while Stratford received 109mm and Mallacoota got 28mm.

The Alpine region also received a reprieve with 45mm falling in Harrietville and Mount Hotham, and 31mm in Falls Creek.

The wet weather arrived in NSW on Monday, and the places that got the most rain were Tumbulgum (243mm), Clothiers Creek (250mm) and Bilambil Height (212mm).

Despite the falls, 100 per cent of NSW remains in drought.

"Because of the drought we're in, we have very dry landscape and just enough of that rain can cause not only flooding but landslips — or essentially soil erosion — so that's certainly something that we're very mindful of," Ms Burford said.

"We still have a number of potentially hot and dry weeks ahead of us.

"There is still that ongoing risk, and while essentially the worst of it is over with that rainfall, we still have a fair way to go."

Stratford was hit with 50mm of rain this morning. ( ABC News: Sarah Maunder )

The fire danger in Victoria will increase tomorrow — in the Mallee it is forecast to be extreme, while in the state's north and north-west it will be severe.

In Gippsland it will be moderate to high.

More rainfall and isolated thunderstorms are expected to hit Melbourne tomorrow night before they move further east later in the week.