MetService says batten down the hatches, or at the very least tie down the trampolines, in the South Island and some parts of the North Island tomorrow.

Forecasters say a cold front will move north in the early morning.

MetService's Karl Loots says there will be severe northwest gales, first hitting the southern South Island in the morning.

"Then slowly spreading up the country and eventually even affecting most of the South Island and then into the Hawkes Bay region and Wairarapa region and Wellington as well, we can see gusts in the canterbury region of up to 160 kilometres an hour."