Thunderstorms dropped nearly 12.5mm on Alexandra and 11.5mm Millers Flat in about 30 minutes about 5.30pm yesterday, causing flash flooding.
Further north Twizel bore the brunt of the wet weather. About 29mm of rain fell at the same time.
A Fire and Emergency New Zealand spokesman said the Alexandra Volunteer Fire Brigade was called to about six flooding incidents around the township.
There were reports of flash flooding on the road between Millers Flat and Ettrick, and rockfalls on the Cromwell Gorge Rd.
MetService meteorologist Tui McInnes said the storms were typical for this time of year.
"Very typical thunderstorms, which form in the afternoon through heating of the earth, and the air rises up and condenses and all that water has to fall somewhere and it just comes straight down."