Police say no threats to Anzac Day in SA

South Australian police say they know of no credible threats to Anzac Day activities across the state but have urged people to remain vigilant to ensure their safety.

Assistant Commissioner Brian Fahy says police are well aware of the recent arrests in Melbourne related to alleged Anzac Day terror plots.

"The reality is we are all living in times where security is something that needs constant monitoring," Mr Fahy said on Friday.

"Our advice to people is just to go about your normal daily lives.

"We also say that in these times to have a particular attention and vigilance about your own safety and security and if you see anything suspicious, report it immediately."

Police will be deployed in record numbers for Anzac Day with those on duty to include undercover officers.

They have also cautioned that it is difficult to prepare for an act of violence that occurs with very little planning by the offenders and without warning.

"In a preventative sense, we would strongly suggest with the high visibility policing strategy that we have tomorrow, that people would be put off from any act of violence," Mr Fahy said.

The RSL said there was no indication that attendances at this year's march and dawn service in Adelaide would be impacted by the recent arrests in Melbourne.

However, numbers could be down because of the weather expected across the state.

The weather bureau has issued a severe weather warning for parts of SA with strong winds and rain forecast for Friday night and early Saturday morning.

It says the worst should have passed in time for dawn services.