One of Victoria's most popular beaches is a no-go zone today as the state swelters through one of its hottest days this summer.
A blue-green algae alert has been issued for Torquay front beach, south-west of Melbourne, after toxic blooms were detected at Cosy Corner.
Authorities urged visitors to avoid all contact with the water and to thoroughly wash any contaminated clothing and wetsuits.
Blue green algae can cause skin irritation and sore eyes, ears and noses in people and pets, and if swallowed, can lead to cramping, nausea and vomiting.
Boating is still allowed but anyone fishing is urged to take caution, including thoroughly washing any fish.
Crabs, mussels, oysters and crustaceans should not be eaten as ingesting toxins could cause serious illness.
Torquay is forecast to reach 32 degrees today but elsewhere in the state, fire weather warnings have been issued as extreme heat grips most of the state.
Mildura was expecting 43 degrees, with temperatures in the low 40s and high 30s from the state's west, across the north and into the central region, including the cities of Bendigo, Shepparton, Yarrawonga, Albury-Wodonga and Melbourne.
At Bright, at the foot of Victoria's High Country, locals and weekend visitors are also being warned not to swim, despite the town expecting 36 degrees.
A water quality warning has been issued for Bright River Pool.
Water quality testing has detected higher than usual levels of E.coli.
The Bright Splash Park has an independent water supply and is safe to use.
Big swell raises lifesavers' concerns
Lifesaving Victoria (LSV) is urging those who are heading to the state's beaches to cool off to respect the surf conditions.
"We've got a big swell running on the coast today, which means the tides are dragging in and pushing out with quite a bit of force," LSV's executive advisor Paul Shannon said.
"You need to keep kids within arm's reach."
He said those who were not confident swimmers or experienced in the surf should instead head to a local pool to escape the heat.
"If you are heading down the coast, don't just pull over on the side of the road and head straight into the water at your nearest destination.
"Search out the red and yellow flags which are going to be around the lifesaving clubs."
It comes after a man died and another was rescued after their boat was hit by a wave and overturned in waters off Barwon Heads, south west of Melbourne, on Saturday.
The Bureau of Meteorology's duty forecaster Bri McPherson said Sunday's maximum temperatures were about eight to 10 degrees above average for this time of the year.
"Unfortunately, the change is not expected to come through until quite late this time so pushing into the south-west of the state from the early afternoon but not really moving through very fast at all and not really getting much traction until late afternoon and into the evening," Ms McPherson said.
"And then it just stalls over much of the state so the change doesn't push through Mildura, for example, until tomorrow morning."
Melbourne was expecting the change in the early evening but the warmer air was not expected to clear the Northern Country and north-east until Monday.
Bushfire risk for north-west
The weather bureau is forecasting an extreme fire danger in the Mallee and Wimmera, where a total fire ban has been declared.
A hot and dry day with fresh and gusty north-westerly winds is expected ahead of a cool but gusty south to south-westerly change during the evening.
The Country Fire Authority's chief officer, Jason Heffernan, said firefighters across the state are on high alert.
"Yesterday was quite warm, clear skies, we haven't had rain for a little while," he said.
"Those grass fire fuels have had some time to dry out and we do anticipate today we will see a number of grass fires occur, as we did see yesterday."
Mr Heffernan said Victorians were good at following total fire bans but accidents can happen.
"It is the weekend, people are out camping and the like and if you did have a campfire, now is the time to make sure you check that it is fully extinguished, cool to touch, always extinguish it with water."