Hurricane Karina strengthened into a Category 4 storm in the Pacific Ocean on Monday, according to the S. National Hurricane Center. The storm, which intensified quickly after becoming a hurricane on Sunday, was fueled by warm waters far offshore. It is not threatening land.

Karina was located about 1,020 miles (1,642 kilometers) west-southwest of the southern tip of Mexico's Baja California Peninsula, with maximum sustained winds of 145 mph (233 kph), the center said. The hurricane was moving west.

No coastal watches or warnings are in effect, but waves from the storm were expected to affect Mexico and likely Southern California. Forecasters said additional strengthening was possible on Monday, followed by fluctuations in intensity.

Elsewhere in the Pacific, Tropical Storm Lowell was about 855 miles (1,376 kilometers) east-southeast of Hilo, Hawaii, with maximum sustained winds of 60 mph (97 kph), moving west. Forecasters said Lowell could become a hurricane by Monday night or Tuesday. The storm posed no immediate threat to land, but the center said it could be in the vicinity of the Hawaiian Islands later this week.

Earlier reports from the Associated Press indicated that on Sunday, Tropical Storm Karina had strengthened into a hurricane with maximum sustained winds of 80 mph (130 kph), making it a Category 1 hurricane. At that time, it was located about 820 miles (1,325 kilometers) southwest of the Baja California Peninsula and moving northwest at 15 mph (24 kph) on a forecast path farther out into the Pacific. A major hurricane is Category 3 or greater.

The National Oceanic and Atmospheric Administration has forecast a below-average Atlantic hurricane season due to El Nino, predicting eight to 14 named storms, with three to six reaching hurricane strength and one to three intensifying to major hurricanes.