Guillermo rapidly gained force to hurricane strength late Thursday night.

The National Weather Service has it coming close to the Hawaiian Islands but isn’t certain whether it will pass north or south or directly hit the state.

“It’s impossible for us to say right now,” said lead forecaster Jon Jeselma. “It’s too early.”

Jeselma said Guillermo does bear watching and could affect the islands with heavy rain, wind and increased surf by the middle of next week.

By 2 p.m. Saturday, Guillermo is projected to reach maximum sustained winds of 110 mph — top speed for a Category 2 storm — and be 1,100 miles east-southeast of Hilo, he said.

Guillermo is expected to cross into the Central Pacific Hurricane Center area of responsibility Saturday.

At 8 p.m. Thursday, Guillermo was about 1,780 miles east-southeast of Hilo, moving northwest at 14 mph with maximum sustained winds of 70 mph. Its winds were at 40 mph earlier Thursday.

Tropical storm-force winds of 39 mph or higher extend outward up to 90 miles from the center, forecasters at the National Hurricane Center in Miami said.

Meanwhile, a tropical depression carrying a mass of moist air is expected to pass south of the state, bringing an increase in humidity and trade showers, especially to Hawaii island, forecasters said.

A small-craft advisory continues for the typically windier areas near Maui and the Big Island. The small-craft advisory is in effect until 6 a.m. Sunday for the Pailolo and Alenuihaha channels, Maalaea Bay and waters south of Hawaii island.

In May the Central Pacific Hurricane Center said there was a 70 percent chance of a busier-than-usual hurricane season, with five to eight storms, due in part to a persistent El Nino. The weather phenomenon is associated with warmer-than-normal sea surface temperatures in the eastern tropical Pacific.

Guillermo would be the first hurricane to approach the isles this season.