The season's first named hurricane was spinning somewhere off the coast of South Carolina early Thursday.
Hurricane Arthur strengthened overnight and had sustained winds of 75 mph as of 5 a.m., according to the National Hurricane Center. It was moving north at roughly 9 mph.
It was expected to move near the Outer Banks of North Carolina by Thursday night, prompting hurricane warnings for much of the coast of North Carolina. By Saturday, the National Hurricane Center predicts, it should be far north and into Canadian waters.
Forecasters have been tracking the storm since last weekend, when it developed into a tropical depression about 200 miles east of St. Augustine. The storm kept rain chances low and temperatures high for much of Tampa Bay as it drew in upper level dry air. At the same time, it kicked up surf and prompted tropical storm warnings for much of Florida's east coast.
Now that Arthur is moved on, forecasters predict a sticky holiday weekend with intermittent afternoon showers and an increased chance of lightning. According to the Bay News 9 Weather Center, Friday will top out at 91 degrees and Saturday and Sunday will reach 92 degrees. The heat index will likely be well over 100 degrees for much of Tampa Bay.
A 50 percent chance of rain is predicted for every day of the long weekend.