Hawes reached the Empress Hut and when Dowall had not arrived by 9.30pm on Thursday, emergency services were called.
The search and rescue operation commenced at 9.30pm on Thursday and will continue tomorrow when it is hoped there will be a significant improvement in the weather.
Police said they were obviously concerned for the wellbeing of Dowall - a New Zealander who is currently living in Myanmar and works for the United Nations - but he was an experienced climber and they hoped he had been able to find shelter.
Mid-South Canterbury Area Commander Inspector Dave Gaskin earlier told the Herald on Sunday the weather in the region was "atrocious".
"There is low cloud, rain and strong, strong nor-westerlies so the helicopter can't fly," he said. "We are still waiting patiently for a break in the weather but not probably expecting that until tomorrow I suspect so we have put everything on hold for today.
"Obviously if there is a break in the weather we will get straight into there but in the meantime we are just waiting to see what develops."
Both climbers had personal locator beacons on them for the climb but Dowall's beacon had not been activated.
Gaskin said rescue crews were hopeful the man would be found alive.
"We are always hopeful and at this stage we believe we are looking for a person who has maybe hunkered down in a crevasse or got out of the weather somewhere but the longer it lasts and the longer we go on without any sign or any indication that he is alright, the more concerned we get," he said.
"Tomorrow is day three and that is a long time to be stuck out in the weather that is out there at the moment. In saying that people still survive for long periods of time if he can get out of the wind and get a bit of shelter he will be fine."
Good friend and fellow climber Nina Sawicki said Dowall was well-equipped with food, a cooker, all he needed to keep warm and emergency gear.
"All we know is he is somewhere near the upper Empress Glacier and the two got separated shortly before Rob reached the hut.
"Steve is very experienced and he may not have activated his beacon because he had dug himself a snow shelter and didn't want to worry anyone. He might have realised it was too dangerous to continue when the cloud came down and he's decided to make himself a shelter.
"People have survived for days in bad conditions so we are hoping with his experience that is what has happened. "
