Unpredictable and forever changing weather is on cards for the month of May, with an early dry spell to be followed by more testing conditions.

'The first weekend in May is forecast to be settled,” says MetService meteorologist Georgina Griffiths, 'but active lows over the Tasman Sea soon bring in some rough and tumble weather.

A month of changing weather patterns is forecast for May.

'Next week is signalled as stormy and wet for most of the country, with an elevated risk of extreme rainfalls in western parts of both Islands, as well as for Nelson.”

By the middle of May, a pattern change to cooler south-westerlies heralds a change to relatively dry conditions for regions in the north and east of both Islands. Temperatures in the first half of May are likely to swing from one extreme to the other - and then settle slightly cooler for the second half of the month.

'After unseasonably mild north-westerlies next week, a rapid change to unusually cool conditions is expected by mid-month,” says Georgina.

'Eastern regions will experience the largest extremes in temperature. 'The unsettled weather we have experienced in April is expected to continue into the first half of May.

'It looks like we are now paying for the settled run we had at the start of 2015.”

April was extremely wet between Waikato and Wellington, while Hamilton received more than twice the usual April rainfall (more than 200 per cent normal). It was also the wettest April on record for Whanganui, Palmerston North and Paraparaumu.

Along the West Coast, Milford Sound recorded over 900mm of rain, and Greymouth and Hokitika were well in excess of 300mm. For May as a whole, above normal rainfall is expected for the western South Island, Nelson and Taranaki to Wellington.

Near normal May rainfall totals are predicted for Southland and Otago, while a drier than usual May is signalled for Canterbury, Marlborough, the eastern North Island and from Taupo northwards.