Federal officials Thursday announced that Long Island is experiencing a "moderate drought."

In fact, this has been the driest April 1 through May 20 at Long Island MacArthur Airport since records started being kept there in 1984, said Samantha Borisoff, climatologist with the Northeast Regional Climate Center based at Cornell University.

There is a precipitation deficit of 4.64 inches since April 1 at the airport.

The U.S. Drought Monitor describes possible impacts of moderate drought to be some damage to crops; low streams, reservoirs, or wells; and some water shortages developing or imminent.

The lack of rainfall means more irrigating is needed for some farmers, a higher chance for brush fires spreading under the right weather conditions, and more garden and lawn watering for homeowners.

The last time the airport recorded more than half an inch of rain was April 20, said Jay Engle, National Weather Service meteorologist based in Upton. That's when a total of 0.86 of an inch fell through the following day.

Even that was no great shakes, as the month itself registered a 2.68-inch deficit, making it the third-driest April on record, Borisoff said.

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May's deficit as of Thursday was 1.96 inches, with only 0.34 inches of rain falling so far.

While conditions have been dry, "it's a little bit early for concern," said Rob Carpenter, administrative director for the Long Island Farm Bureau.

Some farmers are now irrigating nursery trees, shrubs and ornamentals, he said, primarily to moisten the ground to keep the soil in place as workers dig. Similarly, those in planting mode, such as for corn, are irrigating to keep the dust down.

Weather factors that can lead to red flag fire warnings are windy conditions and low relative humidity, with dry fuel also a big factor, said David Stark, also a meteorologist in Upton.

Among the likely causes for the dearth of rain is El Nino, a climate cycle in the Pacific that affects weather patterns worldwide. For the United States, Borisoff said, El Nino "tends to shift storm tracks to the south," which, indeed, saw above-normal precipitation in April.