15/03/2021 Watch: Here's MetService's latest severe weather warnings video. Credits: Image - Getty; Video - MetService The South Island will swing from heavy rain to the risk of frost this week as an unsettled start to the week kicks in. MetService is forecasting a front to start moving northeast over the country on Monday and Tuesday, bringing heavy rain to western parts of the South Island. "Heavy falls for Westland Ranges where a warning is in force. Heavy rain watches are also in place for Fiordland, the headwaters of the Otago and Canterbury lakes and rivers, and Buller as well," says MetService meteorologist Andy Best.