Information technology and telecommunications jobs showed a slight fall of 1.3 per cent in the latest Olivier Internet Job Index.
The nationwide drought and the threat of terrorist attacks have contributed to the drop in the Olivier Internet Job Index of 6.1 per cent in October.
Olivier Recruitment Group director Robert Olivier said there were 3889 fewer ads than the month before, with 14 job sectors recording losses, and just seven rising.
It was the most significant decrease since the last quarter of 2001.
"Senior IT&T people who are still looking for work will find November is their last chance to snap up permanent and contract work for the year. If they don't have a job by then they're likely to face sitting on the beach until February," Olivier said.
"The effect of the drought may be working its way through to the jobs market and the threat of a terrorist attack close to home may have had a knock-on effect on business confidence.
"Boardrooms are preoccupied with disaster recovery and business continuity planning and aren't making immediate employment plans."
Multimedia Internet and graphic design ads plummeted again by 27.3 per cent.