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KAHULUI - The return of the trade winds should temper the temperature extremes that occurred around the state over the weekend, but it will be increasing the wildfire threat, Maui weather analyst Glenn James said Tuesday.

Even as a brush fire broke out at Pulehu on Tuesday (see related story below), a fire- weather watch was issued giving notice of an increased fire hazard.

"The National Weather Service issued a watch, which means we all have to be very, very careful about not lighting any fires right now," he said.

It may appear to be an abrupt change in conditions, after Maui County experienced a record low 64 degrees on Sunday that combined with steady afternoon showers to provide another near record 65 degrees on Monday, before the daytime temperature zipped up to a high of 91 degrees that afternoon.

It was all brought on by a low-pressure trough that was sliding north of Kauai, cutting off the normal trade wind flows, said James, senior weather analyst with the Pacific Disaster Center.

"That trough has moved off to the west and opened the floodgates for a stronger brand of trade winds. At Maalaea (Tuesday) afternoon, we had 40 mile-per-hour gusts. We should be having another few days of stronger-than-normal trade winds," he said.

The high-pressure system sending the brisk trades across the islands is being augmented by a tropical system that's 1,000 miles southeast of the Big Island and moving westward. The low-pressure system is being monitored and could develop into a tropical disturbance.

Even if it doesn't gain strength, James said, the difference in pressure gradients from the high pressure to the north and low pressure to the south will likely augment the strength of the trade winds gusting across Maui County.

On Tuesday, the winds were blowing up to 36 mph at Kahului Airport, blasting at more than 40 mph at Maalaea and even sweeping the Molokai Airport with gusts of 32 mph.

A National Weather Service forecast notice said a fire-weather red-flag warning is based on the strength of the winds, a high drought index and relative humidity below 45 percent. The winds and drought index already are at levels to warrant a warning, and if the humidity falls, a fire warning could be issued later this week.

Small-craft advisories are posted for channels between the islands as well as for Maalaea Bay, with an expectation of wind-generated high surf along east-facing shores.

James, who produces the www.hawaiiweathertoday.com Web site and "Maui Weather Today" at 7:45 a.m. Monday to Friday on cable Channel 55, said the temperature fluctuations over the weekend were the result of the slack winds, which allowed cold air to drain from higher elevations of Haleakala and the West Maui Mountains, while clear skies Monday allowed more ground heating.

The cloud cover and showers that eased the drought conditions in Maui County on Sunday were the remnants of Hurricane Genevieve, a tropical cyclone that dissipated before it reached Hawaii but remained a soggy air mass as it moved over the islands.

That mass has moved off, and the forecast is for strong trades, some windward and mauka showers, but a possibility of decreased humidity and increased fire risks.

* Edwin Tanji can be reached at citydesk@mauinews.com.