Air New Zealand says huge demand for domestic travel this month means its adding capacity totalling around 16,000 seats.
The airline will be changing the aircraft it uses on many Auckland-Wellington and Auckland-Christchurch flights from 171-seat Airbus A320 to the new and larger 214-seat A321.
Customers on those flights will get free in-flight entertainment - normally only available on Air NZ international flights.
For travellers worried about getting stung with an inflated ticket price due to the high demand, the airline has a few tips - the main one being to book early.
"Naturally demand is higher for travel at certain times of the day, for example first thing in the morning," says Air NZ's chief customer and sales officer Leanne Geraghty.
"By flying at different times of the day, customers will find more fare options available.
"We are doing what we can to keep Kiwis connected and have so far sold more than 550,000 seats for under $100 for travel between December and February."
Jetstar's NZ website is currently promoting sale fares for early 2021.