Hurricane Erin briefly strengthened into a Category 5 storm. It is not expected to make a direct hit on the U.S. but will create dangerous surf.

Storms that ramp up so quickly complicate forecasting and make it harder for government agencies to plan for emergencies. Hurricane Erick, a Pacific storm that made landfall June 19 in Oaxaca, Mexico, also strengthened rapidly, doubling in intensity in less than a day.

A Spirit Airlines plane appears to have flown through Hurricane Erin this week when the hurricane was a Category 4 storm with winds well over 100 mph, according to a flight path shared on social media. Spirit Airlines told Newsweek in a statement that the flight operated normally and no injuries were reported.

Hurricane Erin remained a Category 4 storm throughout the day. Here's a look at the latest forecast and spaghetti models.

Hurricane Erin was a Category 4 storm Monday morning and is expected to retain major hurricane status through the middle of the week.

Hurricane Erin has restrengthened to a Category 4 storm as it turns northwest and is expected to remain east of the U.S., according to the National Hurricane Center.

Hurricane Erin has reintensified into a Category 4 storm on Aug. 18, according to the National Hurricane Center. See where Erin is headed.

SAN JUAN, Puerto Rico (AP) — Erin strengthened into a powerful Category 4 hurricane in the Caribbean on Saturday and continues to intensify, the National Hurricane Center said. The storm is 150 miles northeast of Anguilla with maximum sustained winds of 145 mph. It is moving west-northwest at 20 mph (31 kph).

Hurricane Erin is causing evacuations in North Carolina. Here's a look at the latest forecast and spaghetti models.