The hurricane warning extended from Bahia Magdalena southward on Baja's west coast, and from San Evaristo south on the peninsula's east coast, the National Hurricane Center said.
As of 5 p.m. PDT Monday, the center of the storm was about 285 miles south of Cabo San Lucas, Mexico, and the storm was moving toward the northwest at almost 10 mph. Maximum sustained winds were almost 155 mph with higher gusts.
Jimena was a category four hurricane, approaching category five status, forecasters in Miami said. It is expected to remain a major hurricane until landfall.
The hurricane is expected to turn toward the north-northwest with a gradual increase in forward speed. If that happens, Jimena will approach the southern portion of the Baja California Peninsula Tuesday.
Hurricane-force winds extended outward up to 45 miles from the center, while tropical storm-force winds extended outward up to 140 miles, the hurricane center said.
Jimena was expected to produce rainfall of as much as 10 inches over the southern half of the peninsula and portions of western Mexico during the next two days, forecasters said. Isolated maximum rainfall amounts could reach up to 15 inches.
Jimena was forecast to produce a storm surge of large and dangerous waves and significant coastal flooding along the peninsula.