The flood of 1 April 1975 in the Wairau River, Marlborough, New Zealand
A 15-hour period of heavy rain in Marlborough on 1 April 1975 produced a flood in the Wairau River with a return period of 50 years. The rain was associated with a depression which developed in the north Tasman Sea and moved southeastwards towards Fiordland. It began about 0830 NZST (all times are given in N.Z. Standard Time) on 1 April and ended at about 2330 on 1 April with the passage of the cold front. The most significant contributing factor to the large rainfalls was the strong northwesterly surface wind which prevailed over the area from early in the rainfall period.