A new study concludes the frequency of tradewind days in Hawaii has been on the decline over the past four decades, and warns that a dramatic reduction could have big implications for the state’s climate.

In 2009, Honolulu saw 210 days cooled by tradewinds. That’s 81 fewer days than the total in 1973.

The study, conducted by four University of Hawaii scientists, notes that tradewinds — which blow from the northeast — are fundamental to the state’s climate. Tradewinds affect everything from cloud formation to wave height to rain.

UH meteorology professor and state climatologist Pao-Shin Chu, one of the study’s authors, said the decline in tradewinds could be linked to an increase in drought conditions seen in Hawaii over the past 30 years.

"Precipitation associated with moisture-laden northeasterly trades along the windward slopes of the islands contributes" much of Hawaii’s rain, he said Friday in a news release. Chu also said a dramatic reduction in the trades could spur a major change in Hawaii’s climate.

The study, published in the Journal of Geophysical Research, also found that the frequency of easterly winds increased from 1973 to 2009.

Data for the study came from wind gauges at land stations and on four ocean buoys. The data from the buoys showed an increase in tradewind speeds, while also showing that the frequency of trades declined.

The news comes as forecasters are calling for another several days without tradewinds in the coming week. The trades are forecast to stop Wednesday, giving way to light (5 to 10 mph) winds from the south or southeast.

Anthony Reynes, National Weather Service meteorologist, said the light winds could stick around through the weekend. Expect the days to be hazy, he said.