The cloudburst brought intense heavy rain and thunder and lightning to Dunedin about 4pm, causing stormwater systems to back up and water to pool in places around the city.
The MetService recorded 14.2mm of rain in central Dunedin, 12mm in Mosgiel and ''several hundred'' lightning strikes along the east coast of Otago between 4pm and 5pm, Metservice duty forecaster Nicole Ranger said.
Most of the rain fell in a short, sharp burst and kept Dunedin firefighters busy with about eight water-related callouts in about 40 minutes, Senior Station Officer Jason Hill, of Dunedin Central, said.
''It was just all water-related - water coming in roofs, flooding, or water in the fire alarm system, all down to the heavy rain,'' he said.
That included R&R Sport, after staff discovered water coming in through the ceiling, while staff at Alibi, in the Octagon, and Jay Jays clothing store, on George St, were also left mopping up.
In Mosgiel, floodwaters on the main street, Gordon Rd, spilled over the footpath and headed for shop fronts for the second time in a matter of weeks.
Mitre 10 Mosgiel assistant manager Ricky Bray said he used a forklift to place bags of compost around the street when the downpour hit, providing a makeshift barrier against the rising water.
''It was a torrential downpour for a good 20 or 30 minutes.''
The water rose to the edge of shop doors in places, but apparently did not invade any stores, most of which were closed.
''I think the only difference between this time and last time was we reacted sooner,'' he said.
In November, 25mm of rain fell in one sharp burst, sending floodwaters washing into about 12 shops along Gordon Rd.
The flooding was blamed on the limited capacity of the town's stormwater system, as well as beautification work along Gordon Rd, which had blocked escape routes for gathering floodwater.
Mr Bray appeared to be the only person working to clear floodwaters when the Otago Daily Times arrived yesterday, and he questioned why more was not being done.
The Dunedin City Council or its contractors could have closed Gordon Rd temporarily following the downpour while the water drained away, to prevent the problem of bow waves from passing vehicles, he said.
''The fact this has happened again ... it is a huge concern,'' Mr Bray said.
Dunedin City Council solid waste manager Ian Featherston said he was not aware of any consideration for closing the road, and that would be up to the council's roading department. However, a Fulton Hogan contractor was on site monitoring mud-trap grilles in the area to ensure they remained free of debris, and water appeared to be draining away.
The problem was again the ''sheer quantity [of water] coming into the system'', coupled with the limited capacity and changes to the road's layout. Those problems were to be addressed this year and plans were being drawn up for improvements, Mr Featherston said.