Covering period of Monday 31st January - Thursday 3rd February
Dry, warm conditions prevail across much of the country early this week, however MetService is forecasting a dramatic
change for parts of the South Island with significant rainfall forecast from Wednesday.
A low pressure system is transporting warm tropical air towards the western South Island this week, bringing heavy and
prolonged rain which starts spreading from Fiordland to Tasman including the headwaters of Otago and Canterbury from
Wednesday.
Heavy rain Watches and Warnings have been issued for this event this (Monday) morning. An Orange Heavy Rain Warning is
in place for Westland and Buller, valid from Wednesday, while Fiordland, western Tasman, and the Canterbury and Otago
headwaters have been issued a Heavy Rain Watch.
MetService meteorologist Ashlee Parkes explains, “Hokitika and Milford Sound have had their driest January on record
since 1963 and 1997 respectively. The month of January and the beginning of February will be quite the contrast.”
MetService are forecasting significant rain accumulations across Westland and Buller during this event, particularly in
the ranges. There is the potential that the Westland Orange Warning could be upgraded to a Red Warning in the coming
days. Along with Regional Councils and hydrologists, MetService meteorologists will be monitoring the situation closely.
“Heavy rain could cause rivers to rise rapidly, localised surface flooding and slips which when combined with a King
Tide could cause hazardous driving conditions. People are strongly advised to keep up to date with the latest Warnings
and Watches.” Parkes continues.
The heavy rain is forecast to spread across into the central and eastern South Island, the northern South Island, as
well as onto the lower North Island towards the end of the week before becoming slow moving. So although this system
brings significant rain relief to many regions, unfortunately those in the northern half of the North Island will see
little respite from the dry conditions; one or two light showers may sprinkle the northeastern coast, otherwise the
weather remains dry and warm.
Parkes elaborates, “As this low pressure system tracks towards the South Island, warm northeasterly winds strengthen
across Aotearoa. Many will also notice the humidity rise over the coming days as this system drags muggy, tropical air
across the country.”
“We have some heat alerts in place across the country during the first half of this week as many regions see their
maximum daily temperature push into the late 20s and early 30s, with little relief overnight. On Wednesday and Thursday,
Nelson has only a one-degree difference between its daily high temperature of 22°C, and an overnight low of 21°C,” says
Parkes.