Update 5 a.m.

Madeline strengthened overnight to a category 2 hurricane as it continued heading toward Hawaii island.

Packing maximum sustained winds of 100 mph, Madeline was centered 695 miles east of Hilo and 890 miles east-southeast of Honolulu this morning while moving west-southwest at 10 mph.

Forecasters at the National Weather Service expect Madeline to continue strengthening today and Tuesday until slightly weakening Wednesday.

Meanwhile, in the East Pacific, Hurricane Lester also strengthened slightly, clocking in with maximum sustained winds of 125 mph and moving west at 15 mph.

Lester was centered 1,290 miles west of Baja California.

Update 11 p.m.

Madeline strengthened to a hurricane tonight and could remain a hurricane as it passes over or near Hawaii island on Wednesday. Meanwhile, Lester strengthened into a major hurricane as it moves toward Hawaii and threatens to bring more rain and strong winds during the Labor Day weekend.

Forecasters cautioned that both storms could still change course and the exact timing and effect on Hawaii is still not certain.

However, tropical storm warnings could be posted for Hawaii island as soon as Monday.

At 11 p.m., Madeline was about 755 miles east of Hilo and about 955 miles east-southeast of Honolulu with maximum sustained winds of 85 mph.

Madeline is moving west-northwest at 10 mph and could strengthen slightly Monday, before weakening on Tuesday.

Hurricane-force winds extend 15 miles from the center and tropical storm-force winds extend 90 miles from the center.

Tropical moisture ahead of the Madeline’s center should bring an increase in humidity and tradewind showers starting Tuesday. Madeline should pass over or near the Big Island on Wednesday, bringing strong winds and rain.

The weather on other islands will depend on Madeline’s exact path.

East of Madeline, Lester intensified into a category 3 hurricane with sustained winds of 115 mph in the East Pacific. Forecasters said it could get stronger Monday before it moves into cooler waters and begins to weaken.

Lester may also be a hurricane as it gets close to Hawaii.

At 11 p.m., Lester was 1,205 miles west-southwest of Baja California, Mexico, moving west at 15 mph. Hurricane-force winds extend 25 miles from the center and tropical storm-force winds go out 105 miles from the center.

Previous coverage

Tropical Storm Madeline and Hurricane Lester continued to move toward Hawaii on Sunday, raising the risk for a rain-soaked Labor Day weekend.

As of 5 p.m. Sunday, Madeline was 800 miles east-southeast of Hilo and about 1,005 miles east-southeast of Honolulu, moving west-northwest at about 10 mph and packing 65-mph winds.

Forecasters said Madeline could strengthen into a hurricane by Monday before gradually weakening as it continues to approach the islands.

If the storm continues on its current track, humidity and showers ahead of Madeline’s center will begin arriving Tuesday over Hawaii island and Maui and spread to the other islands. The center of the storm could move near the Big Island Wednesday into Wednesday night, bringing tropical storm conditions.

That would potentially coincide with President Barack Obama’s scheduled visit to Hawaii for the World Conservation Congress. The convention, scheduled for Sept. 1 to 10, is expected to bring in several other dignitaries as well as heightened security and road closures around the Hawaii Convention Center and the Neal S. Blaisdell Center.

Meanwhile, Lester was located 1,875 miles east of Hilo and 2,060 miles east-southeast of Honolulu as of 5 p.m. on Sunday. The storm has 85 mph winds and was moving west at 14 mph. Forecasters said Lester could reach Hawaii by Labor Day weekend if it continues its current path.

Forecasters cautioned, however, that the forecast tracks for both storms could change significantly in the next few days and it is still not possible to predict exactly how and when the storms will affect the islands.

The National Weather Service said tropical storm watches may be posted in the next couple of days.

Forecasters noted that the margin of error for Central Pacific tropical cyclones can vary between 185 and 250 miles on the fourth and fifth days of the forecast track.

“There is a large degree of uncertainty with the speed, track, and intensity of tropical systems like this, which can result in significant changes to the types of impacts we could see,” forecasters said.

Moderate trade winds are expected to continue for the next few days as a high-pressure system persists to the north of the state. Wet weather could arrive as early as Tuesday as a surge of deep moisture moves across the state from the east, heralding the arrival of Madeline’s northernmost edge.