Throughout the region, temperatures would drop on Friday by about 10C or more because of a cold front moving up the country, MetService meteorologist Tui McInnes said.
Saturday could be slightly cooler again.
In Hastings, Friday will be 21C with cloud, southerlies and a possible shower. On Saturday it will be 20C.
Waipukurau is also forecast to reach the 34C high on Wednesday, preceded by 28C on Monday and 31C on Tuesday then followed by 30C on Thursday before dropping to 19C on Friday.
Wairoa is forecast to be 27C on Monday, 28C on Tuesday, 33C on Wednesday, 32C on Thursday then 19C on Friday.
On Saturday, there will be rain and southerlies in Wairoa.
Napier is a couple of degrees cooler than its sister city at 28C on Monday, 27C on Tuesday, 31C on Wednesday and Thursday before dropping to 21C on Friday.
McInnes said the summer season, warm air mass above the country and westerlies were influencing the hot temperatures.