"Course conditions have not improved at the Marathon LPGA and it remains unplayable," a tweet from the LPGA said.
"Finishing the tournament tomorrow is not an option due to an unfavorable forecast. The tournament will be reduced to a 54 hole event with Nasa Hataoka as the winner!"
It would have taken Hataoka's rivals some doing to catch the 22-year-old, who took a commanding six-shot lead into the scheduled final round with a 54-hole total of 19-under 194.
She hit 17 of 18 fairways and rolled in eight birdies in her seven-under 64 on Saturday -- swelling the lead she had first seized with sparkling first-round 61 -- the lowest opening-round score on the LPGA in almost seven years.
Hataoka's 19-under total was a 54-hole scoring record for the tournament, one stroke better than the 195 set three times by Pak Se-ri in 1998 and matched by Paula Creamer in 2008 and Yi Eun-jung in 2009.
With inclement weather in the forecast, Sunday's tee times were moved up in a bid to get the round in.
But play was suspended at 9:40 am, and heavy downpours left the course unplayable.
For hours organizers waited it out, hoping they would be able to complete the round, finally calling it quits shortly after 3:30 p.m. local time.
Hataoka, runner up to Yuka Saso in a playoff at the US Women's Open, claimed her first title since the 2019 Kia Classic.
Americans Elizabeth Szokol and Mina Harigae finished tied for second at 13-under par
Germany's Esther Henseleit was fourth on 12-under with Saso, South Korean Amy Yang, Germany's Caroline Masson and American Austin Ernst a shot back.