A group of 25 to 30 people are back down safely after they were stuck at the Mt John Observatory Astro-Cafe in Tekapo when winds picked up to 130km/h this afternoon.
Earth and Sky, the tour company for Lake Tekapo, has a wind restriction of 80 km/h, and when the winds picked up at around 12:30pm everyone was asked to stay inside and roads were closed.
At around 3pm, staff started to lead the tourists back down in smaller groups.
Glenn Cameron was just about to leave the observatory before he was called back up to the cafe for safety. He says everyone is fine now, and some people thought it was fun.
An Earth and Sky spokesperson says the alpine is "really changeable", but the winds seem to be dying.
She says there is no access to Mt John now and the cafe is closed, however night tours may still go ahead depending on the weather.
In January, 27 people had to stay overnight in the cafe building of the observatory and were only able to leave at 5am when winds died down. They were on a night-time observatory tour.
The cafe is glass-walled and sits 300m above Lake Tekapo.
Tourists visit Mt John to look at the southern sky at night through telescopes, with a range of research equipment not open to the general public.