Two powerful hurricanes are menacing opposite sides of the Pacific, with Hurricane Nolo threatening Hawaii and Hurricane Polo bearing down on Mexico’s Baja California peninsula.

Nolo strengthened into a Category 4 storm and was moving south-southwest away from Hawaii, bringing rain to the Big Island and Maui. A hurricane watch was in effect for parts of the Papahanaumokuakea Marine National Monument.

Polo was approaching Baja California as a Category 3 hurricane with top winds of 125 mph. Mexican authorities warned of storm surge, damaging winds and heavy rain, with life-threatening flooding and mudslides possible. Mexico deployed 15,000 security personnel and closed ports along the expected path.

Forecasters said Polo would cross Baja California and then strike the Mexican mainland, possibly bringing heavy rain and flooding to the US Southwest later in the week. Polo had earlier fluctuated between Category 4 and 5 strength.

The twin storms are part of an extremely active Pacific hurricane season driven by a powerful El Nino. Emergency officials on both sides urged residents to follow evacuation orders and avoid floodwaters.