Warmer-than-average ocean temperatures and other meteorological conditions are expected to sustain Hurricane Irma’s strength as the storm, one of the most powerful ever recorded in the Atlantic, barrels through the Caribbean and heads westward, possibly making landfall in southeastern Florida by the end of the weekend.

Hurricane Irma, a Category 5 storm with maximum sustained winds of 185 miles per hour, poses the most serious hurricane threat to Florida since at least Hurricane Andrew in 1992, Jeff Masters, meteorology director of the private forecasting service Weather Underground, wrote in an update on the storm. In fact, Gov. Rick Scott (R) warned Wednesday morning that the “massive storm” could be more treacherous than Andrew, the most destructive hurricane ever to hit the state.

During the day Wednesday, Irma took a slight turn to the east, making it unlikely the storm will cross Florida and move into the Gulf of Mexico. “Because Irma is likely to move up along the east coast of Florida, Georgia and South Carolina, people from the Florida Keys all the way to Cape Hatteras, North Carolina, should prepare to be ready to evacuate coastal areas, starting with South Florida now,” Evan Myers, AccuWeather senior meteorologist and chief operating officer, said Wednesday afternoon.

Irma slammed into the Caribbean islands of Barbuda, St. Martin, and Anguilla, with images reportedly showing catastrophic wind damage. Irma continued to move westward, with its eye traveling slightly to the north of Puerto Rico. Nonetheless, the island was experiencing major damage from the storm. “We have reports that 20 percent of the island is already without electricity,” Puerto Rico Gov. Ricardo Rosselló said at a news conference Wednesday afternoon, according to a news report. Thousands of people also were reportedly without water.

Hurricane-force winds are extending outward up to 50 miles from Irma’s center and tropical storm-force winds extended outward up to 175 miles.

A hurricane with top winds of 185 mph has never been recorded in Puerto Rico. The most recent comparison may be Hurricane Hugo in 1989, which struck Puerto Rico as a Category 4 storm, causing $3 billion in damage and 72 deaths. Irma’s track is expected to be similar but slightly north of Hugo’s.

Even though the eye of the storm is expected to travel north of Haiti, flood-prone areas of the country may be at risk, given the nation’s vulnerability to floods and mudslides. Northwest Haiti, portions of Cuba, and the southern Bahamas could see 8 to 12 inches of rain.

Three major factors are contributing to Irma’s power, according to meteorologists. The area currently has weak wind shear, which means Irma is not losing its potency. The other two factors are warm Atlantic Ocean temperatures that extend deep underwater and high levels of moisture in the air, each of which is a result of climate change.

Irma is moving through areas where sea temperatures are hovering around 85 degrees Fahrenheit, which are ideal for fueling intensification, Masters told PBS NewsHour.

Four other storms have had winds as strong as Irma in the overall Atlantic region, but they were in the Caribbean Sea or the Gulf of Mexico, which typically are home to warmer waters that fuel storms. Hurricane Allen hit 190 mph in 1980. The others — 2005′s Wilma, 1988′s Gilbert, and a 1935 great Florida Key storm — all had 185-mph winds.

The Bahamas government is evacuating six islands in the south because authorities would not be able to help anyone caught in the “potentially catastrophic” wind, flooding, and storm surge. People there are being flown to Nassau starting Wednesday in what the nation is calling the largest storm evacuation in its history, the Associated Press reported.

Hurricane Harvey’s catastrophic impact in Texas and Louisiana now ranks as the worst natural disaster in U.S. history. Hurricane Katrina in 2005 cost an estimated $150 billion in 2017 dollars, and the Texas governor’s office estimates Harvey could cost $180 billion.

If a storm similar to Hurricane Andrew were to strike south Florida in 2017, taking an identical track and at the same intensity, the insured losses alone would reach between $50 billion and $60 billion due to a combination of increased development and asset values, Swiss Re, a reinsurance company based in Zurich, Switzerland, explained in a report issued earlier this year. The overall economic damage from Irma on Florida, if it sustains its intensity and makes a direct hit on south Florida, would range from $100 billion to $300 billion, Swiss Re said.

As hurricanes grow more intense, Scott, Florida’s governor, remains unwilling to say that human activity contributes to climate change. However, scientists have concluded a changing climate is to blame for stronger storms, and if trends continue, these powerful storms will become more common.

“Warming oceans have created a fertile environment for hurricanes such as Irma to grow into Category 5 behemoths,” James Elsner, chair of the department of geography at Florida State University, told News4Jax.com.

This piece was updated Wednesday afternoon with additional information on Hurricane Irma’s impact on Puerto Rico and the storm’s latest projected path.