were displaced by , but on the morning of August 13, the centers had become vertically stacked. At 08:33 UTC, a hurricane hunter flight reported a closed eyewall in diameter. Based on aircraft reports of winds to the west-southwest of the center, Phyllis was believed to have obtained typhoon intensity midday on August 13. By August 13, a mid-level ridge over China began to weaken while a ridge east of Japan intensified. As a result, Phyllis’ forward speed accelerated as it tracked towards the north. In the 24 hours after being designated a typhoon, Phyllis entered a period of rapid deepening, attaining winds of winds at midday on August 14, which would make it an upper-end Category 3 hurricane on the United States-based Saffir-Simpson Hurricane Wind Scale (SSHWS). At 15:00 UTC, aircraft data measured a minimum barometric pressure of . Based on this, the JTWC estimated that the typhoon reached its maximum intensity of , equal to Category 4 status on the SSHWS. The next day, the storm's forward motion briefly slowed as the ridge extended westward across Japan. After turning to the northwest, Phyllis once again accelerated, and on August 16, passed roughly southeast of Shikoku. The following morning, the typhoon moved onshore near the southwestern edge of Shikoku, with winds of . The system weakened to a tropical storm at 06:00 UTC on August 17 over land, and a tropical depression 24 hours later. Late on August 18, Phyllis ceased to exist as a tropical cyclone, although the JMA estimated that Phyllis transitioned into an extratropical cyclone around this time. The agency continued to track the system until August 20 when it was meandering over the Sea of Japan. Impact A minimum pressure of was recorded in Shimizu. Nearby, in Tosashimizu, winds of were observed. Across Shikoku, the storm dropped of rainfall in some locations, with over of rainfall falling in an hour in parts of Kōchi Prefecture. In conjunction with Typhoon Rita, the two storms contributed to the majority of tropical cyclone casualties in Japan during the 1975 Pacific typhoon season. Overall, 77 people were killed and 209 others sustained injures. Train and ferry service were suspended between Shikoku and Hiroshima by up to three hours while All Nippon Airways and Toa Airways delayed 83 and 27 flights respectively. A total of 129 landslides were reported. Roads were cut in 106 places and 23 dikes were damaged.