Balaclava resident John Bradley has been recording rainfall figures for the National Institute of Water and Atmospheric Research (Niwa) for 34 years and his rain gauge for May so far shows 154mm, just 10mm short of the record 164mm in 1987.
The figure was double Balaclava's average rainfall of 72mm, 11 times the monthly low of 15mm in 2007 and above last May's 107mm.
Mr Bradley said the rain gauge last week was catching 25mm a day, with 19mm on Wednesday and another 10mm yesterday.
His records showed that "every four or five years, about 150mm falls at this time of year".
With the forecast of more rain and snow, he did not expect it to take many days before the record was reached.
MetService expects another cold front to cross the South Island today, bringing a return to cold southerlies and showers.
Snow showers were forecast to 400m or 500m from Southland to Marlborough.
Strong or gale-force winds were expected along the east coast.
Conditions should ease later today, with showers clearing in Otago tonight.
Frosty weather is then likely.
Rain gauges in other parts of the city were also filling up, with the airport at 126mm, nearly three times its May average of 45mm and nearly double its maximum May rainfall of 80mm.
Musselburgh was double its average of 68mm, with 142mm, but short of its 218mm maximum rainfall for May.
The rain, hail and snow in recent days had meant a busy time for building maintenance contractors, who have been inundated with calls from home and business owners about leaking roofs.
Marty Duffy, of Jobman, said he had been flat out dealing with leaking roofs.
The jobs ranged from flooding in homes because of spouting blocked by a tennis ball in a downpipe, to perspex roofs smashed by hail.
Hail and snow had also compounded the problem of blocked spouting, he said.
Transit was yesterday advising motorists to take care on State Highway 94 from Te Anau To Milford Sound; extreme care because of snow on the Lindis Pass; State Highway 87, Outram to Middlemarch; Dunedin's Northern Motorway; and State Highway 85 Kyeburn to Palmerston.
MetService was warning motorists that frosty conditions were likely to cause hazardous driving conditions, especially inland, from Sunday.
