As temperatures rise across the country, the horticulture and viticulture sector is being urged to be mindful of water use.
One of the affected areas is Marlborough, where authorities are calling for voluntary water conservation.
The Marlborough District Council said temperatures are expected to exceed 30degC over the next five to seven days, and the spike in the mercury will have a significant effect on the region's water supplies.
Council Operations and Maintenance Engineer Stephen Rooney said it's important that residents are careful about their use of water for irrigation during this period.
"Everyone, including Blenheim residents, should avoid irrigating their gardens or crops during the day," he said.
"If people can reduce their water use voluntarily, we may be able to avoid water restrictions - particularly in the Wairau Valley, Picton, Renwick and Havelock," said Mr Rooney.
The council has also advised river water irrigation users to monitor their usage and river levels closely.
All Marlborough's rivers have minimum flow levels at which consent holders are required to shut them off. Several rivers are rapidly approaching those thresholds.
The Rai River fell below the 1 cubic metre per second (cumec) shut-off threshold on Sunday, and all consented takes from that river must now cease.
"The Wairau River is very close to the 8 cumec shutoff level, and will drop below that level sometime this week - possibly as early as Tuesday."
Most other rivers in the district are dropping, and without rain may also become unavailable.
The council is also advising those in rural areas to check farm equipment, water troughs, reticulation network and water meters regularly for signs of leakage.