Hawke's Bay was treated to a relatively rare sight yesterday, with mammatus clouds forming in the sky.
The clouds, which MetService Metrologist Rob Kerr said are relatively rare, were captured by local photographer Brena Smith .
Kerr said they are caused by downwards drafts, or downwards moving air.
"On Friday there was some good cumulus/cumulonimbus clouds building over the ranges to the east of Napier, which are strong updrafts.
"What goes up must come down, as they say, and the westerly flow aloft pushed the downdrafts over Napier."
For the clouds to be visible, the lower atmosphere has to be dry, and therefore clear.
"In short: moisture-laden downdrafts pushing into a dry lower layer result in these udder-like formations, from which the name 'mammatus' is derived."
Kerr recommended having a raincoat handy this week, even if it is not wet when you leave the house, with the weather set to bring something different to the Bay each day.
"We've got a changeable week ahead, really, a lot is happening this week."
Tomorrow will see a low system move over the North Island, with widespread rain which will hit Hawke's Bay around midday.
"It'll be a dry start to the morning.
"You will see some scattered falls spilling off the ranges as you get into the early part of the afternoon."
The rain will not linger however, and tomorrow evening is expected to be dry again.
Despite the rain, today will be warm, with a high of 21C in Napier, and 20C in Hastings.
Tuesday will see a southerly change moving up the East Coast, which will hit Hawke's Bay in the afternoon.
The change will bring cooler temperatures with it, with an overnight low of 9C, compared with 12C on Monday night.
Wednesday will be the pick of the bunch, according to Kerr.
"Wednesday should be quite a nice day, fairly light winds and reasonably clear skies."
Following the theme of the week, however, the nice weather will not hang around, with another cold southerly sweeping through on Thursday, before going back to fine weather on Friday.
"The overall theme of the week is changeable, everyday is going to be slightly different, nothing is hanging around."
Kerr said the changing weather was typical of spring. He said the country experienced a blocking high recently, which is a period when a high pressure system remains nearly stationary.
"Once they clear out you tend to get a week or so of systems moving through really quickly, and that's quite common in spring as well."