MetService says it will be a lot colder throughout much of the country from Tuesday - particularly in the Christchurch area, which could have frosty mornings later this week.
The forecaster says a weather system pushing northwards over the South Island is bringing cold air.
The overnight lows in Christchurch could dip to freezing point early on Wednesday and Thursday mornings, with temperatures during the day expected to be between 10 and 15 degrees Celsius.
MetService says North Island temperatures should stay warmer, but could fall low enough to leave some frost on the Desert Road later this week.
It says there could be some wet weather towards the end of the week, and even snow on the higher ski fields throughout the country.
