Chilly, wet and frosty start to the weekend as temperatures plunge around the country

November is bringing with it a week of rain and average temperatures, Weatherwatch says.

After a wetter than usual end to September and start to October the North Island has begun to dry out, though Hawke's Bay remains wetter than average.

For the South Island, the Nelson area is seeing more rain than usual, and it doesn't appear to be easing off anytime soon, Weatherwatch said.

Good news for some parts of the country though - parts of Auckland, Canterbury, Wairarapa, Manawatu, Whanganui and Northland look set to be drier than average for the next week, although this does not mean entirely dry.

It's going to be a chilly, wet weekend for parts of the country - though the worst of the rain is expected to hold off for those hitting the pavement in the Auckland Marathon this Sunday.

A cold band of weather is bringing heavy rain up the South Island to the West Coast from today through to the weekend, and will send the temperatures in some parts plunging to frosty levels.

MetService meteorologist Peter Little said in Christchurch temperatures were expected to take a dive from a maximum of 22C today, dropping to just 13 degrees on Saturday, with frost possible in inland parts of the South Island.

"Thunderstorms and hail are also possible about Canterbury during the afternoon and evening," he said. "As the freezing level drops behind the front, snow could fall as low as 800m for a time across the south and east of the South Island."

Rain, forecast for the Garden City, was predicted to ease by Sunday, though temperatures were expected to stay chilly, with an overnight low on Sunday of three degrees.

Meanwhile overnight lows in Queenstown, were brushing freezing, hitting zero degrees overnight on Saturday. The warmest day for the ski town was forecast to be Sunday, with the sun coming out in force, bringing a high of 16 degrees.

But Little said the conditions looked "alright" for those heading to Auckland to take part in the marathon on Sunday morning, "with a few showers and cool southeast breeze forecast for the event".

Aucklanders today should expect a relatively warm sunny day of 19 degrees, but this would cool slightly over the weekend, with highs of 17 degrees across Saturday and Sunday. Scattered showers were also forecast for the weekend, though these would likely clear by Monday.

Meanwhile in the capital temperatures were expected to go from a high of 16 degrees today to just 12 degrees tomorrow, with showers expected to start later today and carry through till Monday.

Heavier rain was also forecast for much of the South Island today - Invercargill is expected to get a reasonable drenching this morning, with the weather easing in time for the end of the weekend on Sunday.