[10] The day after weakening into a Category 1 hurricane, Kay made landfall in the western central Baja California peninsula with winds of around 75 mph (121 km/h).

[11] Shortly after landfall, Kay weakened into a tropical storm, before beginning to move northward as it passed by Cedros Island.

[17] Kay also damaged most of the Baja California peninsula with strong winds and heavy rain, which caused much flooding and mudslides, though there were no reports of injuries.

[19][20] Moisture associated with Hurricane Kay brought widespread heavy rain, flash floods, and damaging winds to the Southwestern United States.

[21] The National Centers for Environmental Information tabulated $7.02 million in damage across four states in relation to the storm with the majority incurred by California.

[22][23][24][25] Abundant moisture associated with the remnants of Kay led to scattered showers and thunderstorms in the Southwestern United States, particularly in California.

[26] A Major League Baseball game between the San Diego Padres and the Los Angeles Dodgers was delayed due to the rain.

A series of flows impacted multiple valleys in Forest Falls, resulting in a cascade of water, mud, and debris.

[29] A team of 120 personnel from various rescue departments were dispatched to search through mud piled 6 ft (1.8 m) deep for the killed person for several days.

[31][32] Powerful winds accompanied the storm's rainfall, particularly in San Diego County, reaching a maximum of 109 mph (175 km/h) at Cuyamaca Peak.

[21] Gale and surf warnings covered the southwestern counties of California, with officials in Long Beach providing sandbags to residents.

[21] Severe beach erosion occurred in Southern California, with some coasts in the Los Angeles area losing 5 ft (1.5 m) of sand vertically.

[33] On September 16, California Governor Gavin Newsom declared a state of emergency for Imperial, Inyo, Los Angeles, Riverside, and San Bernardino counties owing to damage caused by Kay.

[34] Described as an "unusual setup" for Utah in particular, the National Weather Service issued slight and moderate flood-risk outlooks alongside flash flood watches for the aforementioned state along with Arizona, Nevada, and New Mexico.

[40] A nearly stationary thunderstorm produced over 2 in (51 mm) of rain over areas recently burned by the Calf Canyon fire in El Porvenir.