Hurricane Lee has gained further strength over the Atlantic and has reached the highest level of five. The cyclone, which threatens several Caribbean islands, rotated on Friday night with sustained wind speeds of up to 260 kilometers per hour, according to the US Hurricane Center (NHC) in Miami.

Dangerous currents and heavy surf are expected in the coming days on the Lesser Antilles island chain, Puerto Rico, the Bahamas and along the US east coast.

According to the NHC, “Lee” was located around 1,100 kilometers east of the northern part of the Lesser Antilles, which includes Antigua and Barbuda, St. Kitts and Nevis and Montserrat. Meteorologists had already assumed in the past few days that “Lee” would develop into a “very strong, large hurricane” as it moved over the sea north of the islands. Wind speeds of 119 kilometers per hour or more are called a hurricane.

Hurricane season begins May 15 in the Pacific and June 1 in the Atlantic. It ends in both regions on November 30th. Tropical cyclones form over warm ocean water. Global warming increases the likelihood of severe storms.

The strength of hurricanes is measured according to a scale developed by meteorologists Herbert Saffir and Robert Simpson: A Category 1 hurricane reaches speeds of up to 153 kilometers per hour. Level 2 applies up to speeds of 177, level 3 up to 208 and level 4 up to 251. Devastating damage is threatened by a hurricane of the highest category 5, which rotates with a wind speed of more than 251 kilometers per hour. Hurricanes often gain strength as they move over the sea. They quickly lose their strength over land because there is no supply of warm, moist air masses.