A northwesterly airflow strengthens over New Zealand today with a cold front moving onto the lower South Island this evening reaching Cook Strait overnight. This cold front continues northwards over the North Island on Tuesday weakening as it goes, a cold southwest airflow lies over the South Island.

Mostly sunny for a fair amount of the North Island today however expect cloudy areas for some western areas, perhaps the risk of a brief shower or two at times about Taranaki through to Kapiti. Rain becomes heavy this evening for the West Coast of the South Island at which point there may be a rumble of thunder or two. High cloud out east with rain / showers spreading into Southland and Otago this evening with a gusty westerly change. Northwest winds rise to gale later this evening about Cook Strait and also perhaps about some inland parts of Canterbury.

A band of rain / showers moves northwards over the North Island slowly during Tuesday, not reaching Auckland and Northland till the evening / overnight. Early heavy rain eases about the northwestern corner of the South Island, expect showers for most other South Island regions although Canterbury and Marlborough are mainly dry. Canterbury could see a shower or two from afternoon Banks Peninsula northwards. A few sleety showers are to be expected about Southland with a few snow flurries to 400 or perhaps even 300m at times in a cold westerly airflow.

By Weather Analyst Aaron Wilkinson – WeatherWatch.co.nz