The SA Pathology COVID-19 drive-through testing facility at Pridham Boulevard in Aldinga will only operate from 8.30am to 11am today, due to the heat.

The Clinpath drive-through site at Rowley Road will also only operate from 6am to midday.

The forecast high temperature for Adelaide today is 39 degrees.

The Victor Harbor walk-in testing facility is so far unaffected but SA Health say they may close facilities at short notice.

SA Health are advising people who may have to wait in the heat to bring water, snacks, a chair and sun protection.

The expected maximum temperature at Victor Harbor is expected to be 32 degrees.

SA Health advise that people with bookings at testing facilities affected by the closures will receive text messages with further instructions.

Many metropolitan testing services will also be operating with reduced hours today, including Victoria Park and Bedford Park.