An unstable front is expected to bring heavy showers, hail and thunderstorms to much of Nelson and Marlborough on Tuesday afternoon.
Metservice has issued a Severe Thunderstorm Watch for the area, including eastern parts of Tasman, between 2pm and 7pm Tuesday.
A few of these thunderstorms may become severe, producing large hail in excess of 2 cm in diameter or significant hail accumulations, and a slight chance of a small tornado, according to the weather forecasting organisation.
Shower and thunderstorm activity should ease on Tuesday evening.
Large hail can cause significant damage to crops, orchards, vines, glasshouses and vehicles, as well as make driving conditions hazardous.
