Corn grows in dry ground in southwest Washington. A moderate drought now covers 77 percent of the state, the U.S. Drought Monitor reported Sept. 14.

Drought conditions are spreading rapidly across Washington and Oregon, federal officials reported Thursday, though cooler and wetter weather is expected to settle over the Northwest during the last half of September.

A moderate drought prevails over 77 percent of Washington, according to the U.S. Drought Monitor, while the northern 43 percent of Oregon has fallen into a moderate drought.

“This is a snapshot of what’s happening,” Washington State Assistant Climatologist Karin Bumbaco said. “If the forecast of precipitation does happen, I imagine the drought monitor won’t get worse, but it will take some time to pull out of the precipitation deficit.”

Drought conditions have appeared at the end of a hot and dry summer in the Pacific Northwest. Two weeks ago, less than 2 percent of Washington was in a drought, while no part of Oregon was in a drought.

The southern half of Oregon remains untouched by drought.

Portions of Central Washington also are not in drought. “That area is above-normal (precipitation) as opposed to the rest of the state,” Bumbaco said.

The USDA reported this week that irrigated crops in Washington continue to do well, though other crops are showing signs of stress. Some 40 percent of pasture and rangeland was described as “very poor,” according to the USDA.

The reservoirs that supply irrigators in the Yakima River Basin held 114 percent of the normal amount of water for this time of year, the U.S. Bureau of Reclamation reported Thursday. Streams statewide, however, are starting to show the effects of the summer. Some 43 percent of the streams monitored by the U.S. Geological Survey were running below normal Thursday, up from 16 percent one month before.

In Oregon, most livestock were being fed hay because of poor pasture conditions, the USDA reported.

In Idaho, 19 percent of the state is in drought, while 8 percent of California is in drought. The figures were little changed from the week before.

Federal climatologists said that over last three months most areas west of the Rockies have been extraordinarily dry, but that pattern is expected to change.

Odds are that Washington, Oregon, Idaho and California will be cooler and wetter than normal for the last two weeks of September, according to the U.S. Climate Prediction Center.

The center warned that temperatures in the four states probably will be much below normal on Sept. 19-23. Unusually heavy rains are expected in southwest Oregon.