A storm front is moving through Hawke's Bay bringing heavy localised downpours and - so far - more than 100 lightning strikes.
"There's a cold pool of air aloft at the moment, so basically there is some unstable air around and that's just passing over Hawke's Bay now," MetService meteorologist Mark Bowe said.
"That's what has caused the heavy rain."
Bowe said one weather station north west of Napier had reported 8.5mm of rainfall over the past hour.
There had also been 119 Lightning strikes so far today, he said.
"For the rest of the day the rain will turn to showers, so it will be a wet day all round, and snow lowering to 600 metres.
"Although we do have a high of 16c, it will be showery. Heading into tomorrow, the rain will ease to showers in the morning and then the showers will clear in the afternoon to become fine.
"So, there's an improving trend heading into tomorrow and then by Sunday we just have some cloudy periods with possible showers in the evening and then improving again towards the end of the weekend."
For Sunday, the MetService is forecasting showers developing morning, then clearing afternoon and becoming fine, with strong southerlies and a daytime high of 15c.