WorkSafe is urging employers to plan ahead and protect workers against heat illness as Victorians brace for scorching temperatures.

With daytime highs of around 40 degrees expected in northern parts of the state, WorkSafe executive director of health and safety Narelle Beer says employers need to ensure tasks are carried out safely.

"Working in hot conditions can easily lead to dehydration and heat illnesses such as heat rash, fainting, heat exhaustion and heat stroke, which is a life-threatening condition."

Dr Beer says it is crucial employers take all possible measures to prevent or minimise the risk of heat illness.

"This could be as simple as starting work earlier, or rescheduling strenuous work for a cooler day. It also includes providing workers with cold water and regular breaks in a cool area."

Not only must employers think about the impact of hot weather on outdoor workers, but on those working inside.

"Sometimes temperatures in spaces with no air conditioning or poor ventilation, such as a roof space or shed, exceed the temperature outside," Dr Beer adds.

A recent Forkliftaction Safety First column examined the need for hydration as temperatures rise. Check it out here.