Lousy summer weather and the impact of the Christchurch earthquakes cut demand for hotels, backpacker lodges and holiday parks in January.
They also suffered as tourists preferred to stay with family and friends, despite arriving in record numbers for the month from overseas.
The total number of guest nights fell 4.2 per cent to 4.2 million in January despite there being 266,800 short-term visitor arrivals in the country, said Statistics New Zealand.
Chief executive of Motel Association NZ Michael Baines said the reduction in paid accommodation was worrying, as January was traditionally a strong month in the industry.
"In terms of international visitors, it is important to look at the type of visitors coming into the country. The lowering of airfares means we see a lot of people that probably won't spend as much.
"There are also lots of Australians who come over and stay with family and friends rather than pay for accommodation."
In total, there were 1.57 million international guest nights in January, down 7.1 per cent from January 2011. Domestic guest nights fell 2.4 per cent to 2.58 million.
The survey also showed the number of people staying in the South Island dropped again in January, marking an 18-month decline in accommodation figures for the region.
Baines was adamant "a wide range of solutions" would be required to turn this trend around.
"We need to remember that the domestic market underpins the international industry. While international visitors are great, they are very much the bit that goes on top.
"If our domestic market begins to go, we will start to lose the infrastructure which supports the international demand."
Unlike hotels, which bore the brunt of the downturn, falling 7.1 per cent to 1.03 million guest nights in the month, the number of guests staying at motels increased by 2.9 per cent to 1.18 million in January.
Simon Wallace of the Tourism Industry Association of New Zealand attributed this change, which saw more people staying at motels than hotels for the first time since March last year, to the bad weather.
"People can remain much drier in a motel room than in a holiday park or tent. It is also possible that the motels saw a return of commercial travellers, such as those who stayed with them during the World Cup."
Other figures for January showed a 12 per cent drop in backpackers to 476,000. Holiday park guest nights fell 4.5 per cent to 1.47 million.
- additional reporting: BusinessDesk