"If one (storm) is coupled with a big high west of New Zealand it could help drive in a big southerly and again bring in more snow."
Fellow forecaster Richard Green said the recent warm winds over the South Island often preceded snowy events.
Warm winds in winter were often a sign of very large air pressure zones - so extra warm on one side could sometimes mean extra cold on the other.
While farmers planned for snow every year, early snow predictions could be helpful, Mr Green said.
Last year a spring snow storm in Southland killed half a million lambs and collapsed Stadium Southland on September 18.
Mr Duncan said one positive about snow at this time of the year was that it tended to pass quickly.
"Spring is a fast moving season, things don't usually hang around too long."
- NZPA