Thunderstorms and periods of heavy rain could hit the lower North Island and West Coast, and strong winds are predicted elsewhere as a cold front moves up the country.
MetService said there was a moderate risk of storms between South Taranaki and Kāpiti, in northern Westland and Buller, while north Canterbury and Kaikōura faced the prospect of a drenching from mid-morning.
Strong southwest winds approaching gale forces were also predicted for the central North Island and the Tasman district this morning, as well as coastal Otago and Southland later today.
It said a cold front embedded in a west to southwest flow would raise the risks of thunder and lightning.
"This front is expected to bring a strong, squally southerly change, mainly to eastern parts of the North Island.
"For the North Island, the squally southerly change is expected to reach Wellington soon after midday and reach Gisborne late afternoon. Any thunderstorms that occur will be accompanied by brief heavy rain and hail (with snow above 800 metres), and strong, squally southerly winds gusting 90 to 110 km/h for a time, especially about coastal parts of Wellington, Wairarapa, Hawke's Bay and Gisborne."
Snow was also expected to affect the Desert Road, Lewis Pass and Porters Pass through to 10pm tonight.
MetService said the unseasonably cold start to the month for much of the country would slowly ease and near-average October temperatures should return next week.
No severe weather warnings are in force.