A small central dense overcast developed atop the storm and Sandra reached hurricane status early on November 25 after the consolidation of an eye.

Rapid weakening took place on November 27 and Sandra's circulation became devoid of convection as it diminished to a tropical storm that evening.

As the precursor to Sandra traversed Central America, it produced unseasonably heavy rainfall that triggered flooding and landslides.

Initially expecting a landfalling storm, officials in Northwestern Mexico prepared equipment for power outages, closed schools, and evacuated 180 residents.

Sandra's effects largely consisted of light to moderate rainfall; some traffic accidents and landslides resulted from this, though the overall impacts were limited.

As it reached the southwestern Caribbean on November 17, westerly winds associated with the Intertropical Convergence Zone spurred the development of an area of low pressure and extensive convection.

The system emerged over the Pacific Ocean near Nicaragua on November 21; once back over water, convection blossomed near the low's center.

[1] Convection remained largely disorganized over the following two days as the system progressed westward in response to a subtropical ridge to the north.

[1] Aided by high sea surface temperatures of 86 °F (30 °C), ample ocean heat content and low wind shear, the small system quickly intensified into a tropical storm—at which time the NHC assigned it the name Sandra—and developed a central dense overcast.

[1][9] Sandra reached its peak intensity as a high-end Category 4 hurricane around 06:00 UTC on November 26 with maximum sustained winds of 150 mph (240 km/h) and a barometric pressure of 934 mbar (hPa; 27.58 inHg).

Sandra's remnants eventually succumbed to strong shear and opened up into a trough, roughly 60 mi (95 km) southwest of Culiacán, Mexico, late on November 29.

[16][17] This also marked the record-tying 16th hurricane to form in the Pacific north of the equator and east of the International Date Line; this record is shared with 1990, 1992, and 2014.

[1][18] Sandra was also the ninth major hurricane in the Northeastern Pacific proper and the eleventh east of the dateline, both setting a record for the most in a single season.

[1][18] On a global scale, Sandra was the 30th major hurricane and "record-shattering" 25th Category 4 or 5 storm of 2015; the previous records were 23 and 18, respectively, occurring in both 1997 and 2004.

[23] Moisture from Sandra streamed northward into the Southern Plains and Lower Mississippi River Valley and contributed to widespread rainfall and flooding.