Melbourne still has a chance of equalling the record for a run of balmy May days, but it will all come down to the timing of showers.
Monday's top temperature is predicted to be 22 degrees, with showers from the north arriving later in the afternoon. That would bring the run of days over 20 degrees to nine, starting on Mother's Day on May 11.
Bureau of Meteorology forecaster Peter Blake said the May record was 10 days over 20 degrees, set in May 1972.
To equal the record, Tuesday's temperature will have to rise above the forecast 18 degrees.
"It is a chance if we have a look at things – it's a bit early to be definitive," Mr Blake said.
The bureau, he said, would revise Tuesday's forecast by mid-afternoon on Monday, assessing whether the cold front from the south-west would arrive before Tuesday's temperature had a chance to reach 20 degrees.
He said other factors that could affect the temperature included cloud cover, wind temperatures and whether showers fell on the CBD.
If Tuesday's temperature clicked over 20, Wednesday would decide whether Melbourne broke the record, with 11 days over 20.
"It all depends on how much cloud cover we do have – both are a possibility of reaching 20," Mr Blake said.
He said showers on Monday afternoon and evening would come from the north and were not expected to have much impact on the temperature.