Dr Rosemary Lester has issued an alert for the Mallee for today and tomorrow, as well as an alert for the Wimmera tomorrow.

Heat health alerts are issued when the Bureau of Meteorology forecasts temperatures above heat health thresholds for particular days.

Northern Grampians Shire Mayor Kevin Erwin has urged people to drink plenty of water, avoid going outside during the heat of the day and seek medical attention if they were feeling unwell.

He said children or animals should not be left inside parked vehicles.

Cr Erwin said the most important thing was for everyone to look after themselves and each other.

"It is important to ensure the younger and older people in our communities and those people who might be suffering from an illness are being cared for on heat health alert days, because these people are often more vulnerable to extreme temperatures," he said.

"The most important things to do in these conditions are the simple ones. Look after yourself and keep in touch with others, drink plenty of water, keep yourself cool and stay out of the sun.

"Our home and community care team will be paying special attention to all their clients on these hot days but we also encourage our residents to check in with any friends or family who might be particularly vulnerable to heat stress."

Cr Erwin said council could open emergency relief centres in the event of a disaster.

He said council could also extend opening hours for community pools.

He said information about relief centres and pool opening hours would be posted on council's website, www.ngshire.vic.gov.au.