Hurricane Matthew could be one of the most severe storms to hit the US in a decade

Thomson Reuters

Residents buy wooden boards at a store in anticipation of Hurricane Matthew, in Coral Springs

As Hurricane Matthew surges toward Florida Thursday, officials aren't mincing words in warning people to prepare or get out of the way.

Florida governor Rick Scott has warned coastal residents that "this is going to kill people." Evacuations of millions of people have been underway as far north as South Carolina. The National Weather Service has warned that the storm could render some areas uninhabitable for "weeks or months." It's shaping up to be one of the most devastating storms the US has seen in a long time.

There are a few simple reasons for this:

• Florida has had an unusually long run without hurricanes.
• Hurricane Matthew is an unusually powerful storm.
• It's projected to move along the coastline, delivering sustained wind, rain, and storm surge along an unusually wide area.

The first point is fairly simple to understand. Florida has had a bizarre stretch of luck since the very active 2005 hurricane season, with not a single hurricane making landfall in the state until Hermine earlier this year.

Matthew is strengthening as it moves through the warm water of the Atlantic Ocean. You can see how intense it's eyewall is in this video of it pounding Nassau in the Bahamas:

Matthew returned to Category-4 strength Thursday morning. It also has an unusually low internal pressure, which is a proxy for its energy. Only six storms with sub-940 millibar pressure readings have struck Florida in recorded history.

Further, Matthew isn't going to move out over land after its first landfall, which can limit a storm's impact and force it to weaken. Instead, it will move up the coast, potentially making landfall several times and delivering significant surges.

This will lead to very severe flooding, including in usually-dry areas according to the National Hurricane Center. Rainfall will also likely be very intense.

Matthew is expected to reach Florida early Friday, and move up the coast over the course of the weekend. People in impacted areas should follow local warnings.