Fire crews in the North Okanagan believe they have gained the upper hand after an aggressive grass fire threatened two homes and a golf resort near Vernon.

The blaze broke out at around 3 p.m. Tuesday afternoon. Winds pushed it to within 10 metres of two homes before a fire guard stopped the advance and the houses were evacuated.

Thirty-five firefighters worked through the night to extinguish the 35-hectare blaze and say the fire is now estimated to be 70 per cent contained, but they are still trying to establish how it was sparked.

Maria Russell, who lives nearby the Tronson Road fire, was among those evacuated from her home and had nothing but praise for the firefighters tackling the blaze.

"They have been doing an excellent job. It's good to see how dedicated they are and how much work they are doing. It feels comfortable to know they are doing a great job," she said.

At the height of the blaze, more than 75 firefighters and wildfire management crews were on the scene, backed up by helicopters and air tankers brought in from across the province.

Kamloops Fire Centre Information Officer Kevin Skrepnek said at times wind was blowing smoke everywhere, making it hard for crews to see the flames from the air.

"We do have aerial retardent that we dropped around a large amount of it, but we need to go in with ground crews now to build that containment line, so removing any combustible fuels that could get into its path and potentially let it grow," he said.

Skrepnek said fire crews will continue to monitor the situation over the coming days but he expects fire activity in the area to remain largely weather dependent.