Low pressure that today has formed in the Tasman Sea is expected to grow into a large system by the weekend bringing torrential rain, gales and possibly heavy snow.

Heavy rain is likely across northern and western parts of both islands while strong to gale north easterlies spread over a number of regions. 

However as the low moves eastward the winds may turn to bitterly cold south easterlies – possibly bringing heavy snow in to Canterbury and the Southern Alps on Monday or Tuesday.

The Weather Watch Centre will be closely monitoring the low and we’ll have a more extensive forecast tomorrow morning.