But not before a little more heat.

The Bureau of Meteorology expects a south westerly change to arrive in Ballarat about midday today.

A warm night was expected last night and the mercury is predicted to reach 32C in the city this morning.

The change will bring to a close the city's first real taste of summer heat since an unseasonably warm November.

After a hot weekend, city residents got little relief overnight Sunday.

Ballarat's overnight low was reached at 6am Monday morning, when the mercury dipped to a mild 16.5C at the airport.

But for most of the evening temperatures hovered in the mid-20s.

At 9.30am yesterday, the temperature had already reached 31C at Ballarat Airport, and by 11.30am, it hit 35C.

Wind speeds of 35kmh from the north, gusting up to 54kmh, were recorded before midday.

The city's top of 39.8C, just below the forecast maximum of 40C, was reached just after 4pm.

Rail commuters from Melbourne to Ballarat were among those to feel its effects.

V/Line ordered all its trains to run on heat speed restrictions from 12pm-8pm, cutting maximum speeds from 150 kmh to 90 kmh, delaying services from four to 20 minutes.

Bureau of Meteorology forecaster Terry Ryan said hot air from Western Australia had reached the eastern states in recent days, causing the heat.

And while today's change would bring the heat down, little rain is expected.

"There's just a chance of a shower as the change comes through and then becoming cooler," Mr Ryan said.

Only a few cases of heat-related illness were recorded at Ballarat Health Services Base Hospital.

The hospital's emergency department director Dr Jaycen Cruickshank said most people seemed to be heading advice to take care in the heat, but doctors had treated some cases of sun-stroke in recent days.

"Ballarat's UV index has been reaching extreme levels lately, which can result in third degree burns," Dr Cruickshank said.

"Sunscreen alone doesn't provide full protection, so make sure you re-apply every two hours, or more often if you're sweating, and use a hat, protective clothing and sunglasses."