Some Auckland residents have been caught off-guard by the hot weather, and tank water supplies are already running low.
A Kumeu resident said their tank had never been so low in December before and they were struggling to find a supplier to refill it.
Quality Water Supplies, which provides water to Waitakere, Taupaki and Waimauku is fully booked until the first week of January.
Company manager Bev Speedy said the start of the summer had been hectic.
"Because we've had a wet winter I think people automatically thought their tanks were okay and then all of a sudden we've had this dry spell and they've been caught unaware.
"We're fully booked up until Christmas and then the first week of January is also booked so if people need water they need to call and book in pretty quickly," Ms Speedy said.
Ms Speedy has been supplying water for 18 years and said she had never seen it this busy in December before.
Other companies also said they were struggling to keep up with calls due to the summer rush.