Frosty evenings will linger for most of the week, with overnight lows a chilly 1-3C.
"Residents may notice one or two showers throughout Wednesday and Thursday and they may be heavy at times.
"Wednesday will be fine at first and then high cloud will increase throughout the day, then you'll have brief evening rain with gusty northwesterlies. That's probably what people will notice the most as time goes on, especially in exposed places."
Southern areas of Hawke's Bay are more likely to have heavy showers, while areas such as Napier and Hastings would get sporadic rain and sunshine as the day continues.
"Thursday's weather will be very similar to Wednesday, but it will be slightly backwards. There will obviously be some cloudy periods and a few showers for both days, it'll bring a little dose of rain in, but nothing major."
As for tornadoes, Clark says, surprisingly, they're not unusual in New Zealand.
"Hawke's Bay is pretty safe from that kind of weather, you might get the edge of it, but the region is pretty well protected.
"They happen in areas like New Plymouth and towards Waikato/Bay of Plenty areas. They usually appear when an active front is taking place.
"They happen when the wind changes direction very quickly when you're close to the surface, so it happens on the western coast and the eastern parts of the Bay of Plenty as well. With the updraught of those thunderstorms and the extra wind-share, it starts creating that extra column that produces tornadoes."