The National Weather Service is saying there’s a 35 percent chance that Hilo will experience tropical storm-force winds by Monday.

Tropical Storm Darby, with maximum sustained winds of 50 mph, was 810 miles east of Hilo at 5 p.m. Wednesday, moving west at 13 mph, and could reach Hawaii island by Saturday.

But National Weather Service meteorologist Bob Burke said Darby likely will swing to the northwest before reaching the Big Island.

In the past week, Darby has weakened from a hurricane with sustained winds of 80 mph to a tropical storm.

A turn to the north could still bring heavy rain and humidity similar to, or a little more intense than, the weather over the past two days.

If it passes south or over the islands, there could be stronger winds and heavier rain because the heaviest precipitation associated with a storm is generally on the northeast or northwest section of the system and the strongest winds are near the center of the storm.

As Darby nears, the Big Island and the windward and mauka areas of the Hawaiian Islands could see an increase in rainfall and windy weather.

Darby’s biggest impact will be larger swells on east-facing shores, forecasters said.

While the storms so far this season seem relentless — Tropical Storm Estelle is following Darby — Burke said there haven’t been any significant changes in this year’s hurricane season.

“By this time last year, we only had three systems in our area,” Burke said. “Not really a big difference from early in the season last year.”

All of the hurricanes and tropical storms so far this season formed in the Eastern Pacific and, according to Burke, these systems tend to weaken by the time they approach Hawaii.

However, he said it is still early in the season and the period between August and October is when the Central Pacific is most active. Cyclones that form in the Central Pacific get Hawaiian names, with the next being Ulika.

“We have a long way to go to see what’s going to happen,” Burke said. “We’ll see whether they form in our area or further in the Eastern Pacific.”

Estelle remained at tropical storm strength, with sustained winds of 70 mph, about 965 miles west-southwest of Baja California. Estelle is moving west at 13 mph and is expected to weaken into a post-tropical cyclone by the weekend.

Forecasters at the National Hurricane Center are also watching two other areas of thunderstorms southeast of Estelle that could develop into tropical cyclones in the next five days.

Meanwhile, Honolulu reached record rainfall on Tuesday as the remnants of Hurricane Celia brushed the isles. The rainfall total was 0.33 inches, a record for the date and three times the earlier record, 0.11 inch, set in 2014, the National Weather Service said.

Star-Advertiser reporter Dominique Times contributed to this report.