With this summer predicted to be hotter and drier than usual, vulnerable and isolated South Australians are being encouraged to register for the Red Cross Telecross REDi service.

The free service supports those on its register cope with extreme weather events - including heatwaves - by providing daily wellness calls from trained Red Cross volunteers.

This potentially life-saving phone call is available to older South Australians, people who live alone, have a disability, are experiencing mental illness, are housebound, frail, aged, recovering from an illness or accident, or have an ongoing illness, such as diabetes or a heart condition.

The specially trained Red Cross volunteers ask the clients questions including providing advice on how to stay safe in the heat and ambulance assistance if the client needs immediate help.

More than 18,000 calls have been made to at-risk South Australians since the service began in 2016.

Department of Human Services Acting Executive Director of Community and Investment Support Caroline Lock encouraged people to sign up to Telecross REDi ahead of summer.

"Some South Australians - including people who live alone or live with a disability or mental illness - may be at greater risk from extreme weather events, and we are once again working with Red Cross to make sure they are looked after," she said.

Feedback about the service has been overwhelmingly positive, including, "I feel better because I know someone's thinking of me and if I don't answer that someone will come and check on me," to "it's nice to have someone check on me when my children aren't able to and to remind me to drink more as I'm getting forgetful".

The  Red Cross also provides tips for staying cool during a heatwave:

• Stay indoors: keep out of the heat if you can.
• If you need to go outside, wear light clothing and a hat, put on sunscreen and take water with you.
• Do daily activities like shopping and gardening early in the day or ask someone to help you.
• Draw blinds early in the day.
• Turn your air-conditioner on before the room heats up
• Take cool showers and splash yourself several times a day with cold water, or use a damp cloth.
• Go to an air-conditioned building in your local area to cool off: a shopping mall, community centre, cinema, library or swimming pool.

To register, phone 1800 188 071 or visit the Red Cross website.

For more information about how to prepare and cope with a heatwave, visit  the Red Cross website.