The tropical cyclone moved northwestward at 8 to 10 knots for the next two days. It became stronger from 25 knots to 80 knots during a 36-hour period. It had a ragged eye appearing on satellite imagery just before landfall on the afternoon of June 29. It had a peak intensity of . This made Boris a moderate Category 1 hurricane. The center crossed the south coast of Mexico midway between Lazaro Cardenas and Acapulco. Boris quickly became weaker. It became a depression and turned southwestward in response to a building ridge to its north. The system was disrupted by the mountainous terrain of Mexico and dissipated on the July 1 after moving back over water just south of Puerta Vallarta.