Play was stopped early on Thursday after trying conditions at Dundonald Links.
Former US Women's Open champion A Lim Kim and American Megan Khang each shot 68 to be the Australian's closest challengers.
Lydia Ko, coming off her Olympic golf medal that put her into the LPGA Hall of Fame, battled the worst of the weather but still managed five birdies in her 69.
The opening round was suspended by bad weather and a water-logged course.
Englishwoman Lily May Humphreys is at four under with six holes still to negotiate. Play was halted at the start for about an hour because of rain, and there was another weather delay of two hours, 20 minutes.
Lee is coming off a disappointing Olympics outside Paris where she was never in the hunt and wound up in a tie for 22nd.
The West Australian played bogey-free on a tough course, picking up birdies on both par-5s on the back nine.
"Always a happy girl after a bogey-free round," Lee said. "I feel like I played smart golf, I'd say.
"I gave myself a lot of opportunities for birdie. I feel like when I was in trouble, I kind of missed it in the right spots and could get up-and-down, so that was good."
Lee feels she caught a break not having to deal with the brunt of the rain, although there was no escaping the fierce wind.
"I like the creativity of links golf," said Lee. "There was a lot of wind today so it was playing like a true links golf course.
"Sometimes we don't get as much wind but today was blowing a gale and picturing the shots and having to execute those shots - I didn't find it fun to play. Just when you execute it correctly, you get rewarded."
Ko got the worst of both, describing the weather as so chaotic she was too busy dealing with it to get overly stressed.
"If it's just windy, it's fine. But it was windy and rain," Ko said. "It's hard when you have to hold the umbrella sideways and not up. I'm pretty sure it was built for you to hold it like vertically. So it's just very difficult out there."
Still, Ko had no complaints given the weather.
"That's just part of the experience of coming over. If you don't like it, you're probably not going to play that good, anyway.
"So it's just more about grinding it out and know that sometimes you're not going to be on the fairer side of the draw. But that's also part of playing tournaments over in this part of the world."
England's Charley Hull was contending for the lead until a bogey on the par-5 14th slowed her momentum. She wound up in the group at 70 that included German Esther Henseleit, who won the silver medal at the Paris Games.
The tournament is the final stop before the Women's British Open next week at St Andrews.
Australians Stephanie Kyriacou, Gabriela Ruffels and Kirsten Rudgeley are one under having completed 18, 17 and 13 holes respectively, while Grace Kim finished at even par.
