The Norwegian world number six recovered from a lone bogey with three birdies on the back nine as winds again swept across the Ko Olina Golf Club.
That round left the 10-times LPGA winner at 10-under on 134 after two rounds, a shot ahead of defending champion Ai Miyazato.
The Japanese had five birdies in a late six-hole run.
"It was definitely windier than yesterday, so it was pretty tough out there," Miyazato said. "I grew up in the wind and I like to play in this wind. This morning when I get to the golf course I'm like, 'Now I'm in Hawaii.'
"Hawaii is always windy place and always fun to play this weather conditions."
Last month's Kia Classic winner Beatriz Recari and South Koreans Hyo Joo Kim and Hee Kyung Seo were three strokes back.
Overnight leader Ariya Jutanugarn, 17, fell to five-under after a second-round 75. She had shot a stunning 64 a day earlier.
"I hit a lot of bad shots today," she said. "I cannot control my irons and I still miss a lot short putts."
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