"Today's really cold during the tournament, so all the clubs like 5 yards shorter than yesterday," Kim said. "So it's a little bit tough to judge the distance today, but I try to keep the focus on distance, how to make the right distance."
Known for an attacking style that has led to two of the three lowest 72-hole scores in LPGA Tour history, Kim has been forced to play more cautiously at tight and tricky Lake Merced, with shifting wind and challenging pin positions making it even more difficult.
"It's really tough to escape from the rough because today's pin positions really tough," Kim said. "Just try to get the right number, that's all key today. ... Some holes I have to avoid the pin. But I try to attack the pin, but I couldn't because I miss it (fairway) on some holes."
She has seven LPGA Tour victories, the last a year ago in the Thornberry Creek LPGA Classic in Wisconsin when she shot 31-uner 257 to break the LPGA Tour record of 27-under 261 she shared with Annika Sorenstam.
Charley Hull was second after a 70. The Englishwoman missed a chance to pull closer when her 6-foot birdie try on 18 slid left.
"The wind kind of got up. It was quite windy," Hull said. "The greens, they're quite fast downhill. You got be below the pin. ... I feel like it's more of a challenge, not as much of a birdie-fest."
Puerto Rico's Maria Torres was 5 under after a 71.
I'm freezing a little bit," Torres said. "It was interesting, the final nine holes, with the cold and a little bit of wind, but started playing, trying to be patient out there, trying to keep it simple."
Minjee Lee, coming off a victory Sunday in Los Angeles that moved her to No. 2 in the world, had a 67 to match Lexi Thompson (69), Amy Yang (70), Louise Ridderstrom (72) and Eun-Hee Ji (73) at 4 under. Second-round leader So Yeon Ryu shot a 79 to drop into a tie for 20th at even par. She had four bogeys and a triple bogey on the par-4 16th.
"This golf course is very challenging," Thompson said. "And then they're tucking some of these pins and putting them on three degrees of slope, so it's hard. And then once it starts blowing, it's hard to get it actually close to these hole locations. And just lining up putts and taking your par and running. So, it's just a challenging golf course in general."