Mr Law said the low temperature helped to create a "real nice, crisp start to the day".
"You've got lovely blue skies for the day so you will have a nice day in Tauranga but another cold one to come tonight."
Mr Law said temperatures were expected to drop to about 2C again, with no cloud cover to help seal in any heat.
The cold nights were the result of a cold front sweeping its way up the country, with snow and sub-zero temperatures creating havoc in areas such as Dunedin and Otago.
Mr Law said high pressure building from across the Tasman Sea also helped to push away any active weather, meaning any heat from the day "just disappeared".
However, the night time temperatures should pick up through the rest of the week with north westerly winds expected from early Thursday, Mr Law said.