The 22-year-old South Korean played in the final group off the first tee Thursday in the second round and will now play in the last group on Friday after her brilliant round.
Hwang opened eagle-birdie, dropped a stroke on the fourth and had eight more birdies to get to 15-under 129.
Playing on a sponsor invitation, Hwang has two victories on the Korean LPGA.
"First of all, I broke my life-best score," Hwang said. "At the same time, I broke the course record, so I feel very good."
Hwang matched the tournament record of 62 set by Lizette Salas in the 2013 final round and Cristie Kerr in the 2017 third round, both at Ko Olina Golf Course.
"I feel very different about the course, first, especially the grass type," Hwang said. "It's very different to Korea and play in Korea LPGA."
First-round leader Akie Iwai of Japan followed her opening 64 with a 68 in the afternoon session to join American Jessica Porvasnik (65) at 12 under.
"Feel like little difference, specific on the green," Iwai said. "Getting hard to see the line."
Porvasnik played in the first group of the day of the first tee. She's a 30-year-old LPGA Tour rookie after finishing fourth last year in the Epson Tour standings.
"I just hit a lot of fairways, a lot of greens, gave myself a lot of great looks, and made a few of those," said Porvasnik, a former Ohio State player.
Iwai played in a group with twin sister Chisato, who was eight under after a 66. The 23-year-old Japanese sisters have each won this year as tour rookies. Chisato broke through at Mayakoba in Mexico in May, and Akie won the Portland Classic in August.
Nasa Hataoka of Japan and Australia's Gabriela Ruffels each shot 69 to get to 10 under.
Ruffels, who is tied fourth, made four birdies and a bogey on the front nine. The 25-year-old birdied the 10th, but was stung by back-to-back bogeys on the 12th and 13th which set her back.
A birdie on the 17th left her five behind runaway leader Hwang.
Second-ranked Nelly Korda was eight under after a 67 in the morning.
"The main difference between today and yesterday was just the putts dropped," Korda said. "It was a little gustier out there today versus yesterday, so it was fun to play in, kind of show my creative side."
Coming off a seven-victory season, Korda hasn't won this year and has lost her No.1 ranking to Jeeno Thitikul. The tour has had a different winner in all 24 of its official tournaments this year.
Charley Hull, playing alongside Korda, was seven under after a 68. Hull won the Kroger Queen City Championship three weeks ago in Ohio after Thitikul four-putted the final hole.
Australians Hira Naveed (72, 70) is at two under, while Robyn Choi (71, 72) and Cassie Porter (69, 74) made the one-under cut on the line.
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