Hurricane Idalia upgraded to Category 3 storm: US weather agency

Idalia is likely to still be hurricane while moving across southern Georgia & possibly when it reaches the coast of Georgia or southern South Carolina today

Hurricane Idalia was upgraded to a Category 3 storm early Wednesday as it moved towards northwest Florida, the US National Hurricane Center said.

Tropical Storm Idalia strengthened into a hurricane on Tuesday and forecasters are forecasting it to become "extremely dangerous" before making landfall on Wednesday in Florida, US. (AFP)

"Idalia is a category 3 hurricane on the Saffir-Simpson Hurricane Scale. Additional strengthening is forecast, and Idalia is forecast to become a category 4 hurricane before it reaches the Big Bend coast of Florida this morning," the weather agency reported in an advisory issued at 2:00 am EST (0600 GMT).

"Hurricane Hunter aircraft data indicate that maximum sustained winds have increased to near 120 mph (195 km/h) with higher gusts," it added.

"Idalia is likely to still be a hurricane while moving across southern Georgia, and possibly when it reaches the coast of Georgia or southern South Carolina late today."

Authorities in Florida had earlier described Idalia and its potentially deadly storm surge as a once-in-a-lifetime event for the state's northwest coast, ordering mass evacuations and issuing flood alerts ahead of its projected landfall.

Warm waters in the Gulf of Mexico are expected to further turbocharge Idalia, with wind speeds of 130-156 miles per hour forecast, the NHC said.

It warned of potentially disastrous storm surge inundation of 10-16 feet (3-5 meters) in some coastal areas.

Storms that are Category 3 or higher on the five-level Saffir-Simpson scale are considered to be major weather events.

Scientists have warned that storms are becoming more powerful as the world warms due to climate change.