Melbourne could be set for its wettest day of the year so far, with heavy rain and possible thunderstorms expected to hit the city from about 8pm on Sunday.
The Bureau of Meteorology expects the rain to start falling, moderately at first, from about 5pm or 6pm.
Senior forecaster Michael Efron said the rain would become "quite heavy during the evening. We're still looking at 10 to 25 millimetres across the metropolitan area, until the end of the day.
"It looks really wet between about 8pm and midnight."
The wettest day of 2017 so far has been the 24 hours to 9am on January 20, when the city received 22.6 millimetres.
"We could eclipse that if we do get some of those thunderstorms over Melbourne," Mr Efron said. "But it does look particularly wet across central Victoria, as well as into elevated parts of Gippsland, as this system moves in throughout the day.
"As well as the rainfall, we could see some thunderstorms tonight, as well across a lot of the state."
Us: Rain rain go away come again another day
— BOM Victoria (@BOM_Vic) February 4, 2017
Rain: OK see you tonight#MelbWeather #CantLiveWithItCantLiveWithoutIt https://t.co/SNEhci3iKT pic.twitter.com/khL63HpziE
Despite the forecast, ticketholders to Melbourne Zoo's twilight concert tonight have been told the show will go on.
Umbrellas, however, have been banned. The email alert recommended people bring waterproof tarps instead.
"Please be prepared for wet weather conditions expected this afternoon and to possibly continue throughout this evening," the email said.
"We recommend raincoats, hats, gum boots for dancing shoes, and, possibly swapping your picnic rug for a waterproof tarp to enjoy the show."
The rainfall will be a welcome relief for emergency services, which have responded to a series of bushfires across Victoria this weekend. A fire at Diggers Rest on Melbourne's north-west fringe threatened homes and burnt near the Organ Pipes National Park.
Inquiries by fire investigators into the cause of the fast-moving grassfire have established that it was ignited by a ride-on lawnmower.
CFA state duty officer Jamie Hansen said the blade assembly of the lawnmower "malfunctioned and created a spark. The mower was mechanically unsound".
The fire, which broke out about 11.20am, burnt about 110 hectares and had a perimeter of eight kilometres. It was tackled by 170 firefighters, 33 firefighting vehicles and four aircraft.
"We had gusty north-westerly winds, and that, coupled with difficult terrain and the gullies in the area, [meant] we had quite erratic fire behaviour, which made it very difficult to control," Mr Hansen said.
"It was brought under control at six o'clock last night, and then early this morning we've declared it safe.
"There's been no loss of homes in the area. There were a few homes that had superficial damage, and there's obviously a lot of fencing that has been destroyed."
Mr Hansen said the grassfire was a prime example of the kind of threat grassfires could pose this summer "with the weather conditions the way they've been. The fuel in the grassland areas has increased significantly this season."
Authorities responded to two other grassfires on Sunday, including one at Tooradin, south-east of Melbourne. Authorities said the fire was under control about midday on Sunday.
The fire burnt about four hectares. "It was caused by a stolen car left in a paddock and set alight," Mr Hansen said.
In the La Trobe Valley, fire crews responded to a grassfire at Hazelwood North. The fire, which is being treated as suspicious, was quickly brought under control.
The thunderstorms expected to hit Victoria late on Sunday could bring lightning strikes, but the expected heavy rain will reduce the risk of fires caused by any possible strikes.