Hawai'i has the worst drought conditions in the country, and those are expected to continue through spring, according to federal weather and climate agencies.

The hardest-hit areas are west Moloka'i and leeward portions of Maui and the Big Island, according to the U.S. Drought Monitor. With most rain gauges across the state reporting less than 50 percent of normal rainfall last month, drought conditions have worsened in or spread to several other areas, said Kevin Kodama, senior service hydrologist at the National Weather Service in Honolulu.

The El Niño phenomenon — a periodic warming of water in the tropical Pacific — is responsible for the below-normal precipitation , according to NOAA's Climate Prediction Center.

O'ahu is the only major island in the state without any areas under a drought classification on the latest Drought Monitor map.

The map shows the eastern half of the state continuing to bear the brunt of the dry spell, with "extreme" drought conditions persisting in the South Kohala and leeward North Kohala areas of the Big Island, the south and west portions of Maui and the western third of Moloka'i.

Drought conditions over southern sections of the Big Island have worsened to the "extreme" category in recent weeks.

"Severe" drought is affecting central Maui and portions of North and South Kona and Ka'ū on the Big Island, while the lower Kona slopes and the entire island of Lāna'i are experiencing "moderate" drought conditions.

In recent weeks, the windward sections of the Big Island and northeastern third of Kaua'i also dropped into the "moderate" category, placing more than three-quarters of the state under at least moderate drought, according to a statement released by Kodama.

He said the dearth of moisture has degraded pastures to the point where ranchers on Maui and neighboring Moloka'i are losing cattle and having to cull herds more than normal so the remaining animals have enough to eat.

Water levels within the Kualapu'u Reservoir in west Moloka'i remain low and a mandatory 20 percent reduction in irrigation water use remains in effect.

Upcountry Maui residents have been asked by the county Department of Water Supply to reduce water use by 5 percent and Central Maui residents by 10 percent.

Kodama noted that the dry conditions also have increased the risk of wildfires in the western and southern sections of the Big Island, already hit by several blazes in the past couple of months.