Emerging into the eastern Pacific between the September 10 and September 12, an area of thunderstorms developed southeast of an upper level cyclone off the southern tip of Baja California Sur due to the interaction of the upper cyclone with the pair of tropical waves.

By the September 15, the thunderstorm activity organized into bands, indicating the presence of a new tropical depression, the eleventh of the season.

Proximity to land and west to southwesterly vertical wind shear weakened the cyclone, and Ignacio regained tropical depression status late on the September 18.

[2] Ignacio was centered around 45 km (28 mi) offshore and was near its peak intensity of a minimum central pressure of 994 mbar (29.4 inHg) on the evening of September 17.

[2] Ignacio weakened quickly on September 18, probably due to the combined effects of the storm's close proximity to land and persistence of waters likely cooled by upwelling.

The remnants of Ignacio, identified on satellite imagery as occasional flare-ups of convection, moved west-southwestwards over the next two days.

[2] When Ignacio was closely approaching the coast of Mexico, a tropical storm warning was issued from Zihuatenajo to Cuyutan on September 16.

[6] The remnants of the storm caused several dams to burst in the state of Chihuahua, leaving 10,000 people homeless and killing another 13.