A low pressure system moves into the Tasman Sea today with a north to northeasterly airflow lying over New Zealand. This low deepens to sit just west of the country on Tuesday, flinging a cold front over the upper South Island and North Island bringing in some heavy rain, possible thunderstorms for the North Island too. Most of the lower South Island is wet also, slowly clearing about Southland from afternoon.

Showers for the upper and western North Island today, becoming heavy for some this afternoon with possible thunderstorms (mainly inland areas). The east coast has high cloud, spots of rain spread from the west at times, mainly this afternoon. Light showers turning to rain this afternoon for northwestern parts of the South Island, rain spreads southwards into South Westland late afternoon / evening before becoming heavy at night. Mostly cloudy in the east, the odd light shower or drizzle patch from afternoon (more so inland), showers or patchy rain more likely from evening.

Showers turning to rain late morning on Tuesday for the upper North Island, rain may be heavy with possible thunderstorms then easing late afternoon as gusty northerlies tend northwest. Rain about Taranaki spreads to other lower western North Island areas late afternoon or evening. High cloud in the east then rain spreads from the west in the evening. Rain about Nelson and perhaps Marlborough at times will be heavy now and then before easing overnight. Rain for the rest of the South Island, possibly heavy about the Alps. Morning showers for Southland then drying out from afternoon.

By Weather Analyst Aaron Wilkinson – WeatherWatch.co.nz