Summer hasn't even officially arrived yet, but most of the Upper Colorado River Basin is already hot and parched, according to federal weather experts.

The National Integrated Drought Information System says in its most recent weekly assessment that temperatures in the basin are above average, and precipitation and stream flows below normal. The basin includes Colorado, Utah and Wyoming.

In keeping with recent reports showing this spring was the warmest on record, the June 12 assessment, which was presented and fine-tuned by climatologists during a webinar this morning, shows most of the basin saw higher-than-usual temperatures last week. Western Colorado is feeling the heat the most, with temperatures 4 to 8 degrees Fahrenheit above average. Conditions in northern Utah were slightly cooler than average, but most of the region is abnormally warm.

The Upper Colorado Basin is becoming drier as well. During May, much of the west slope of Colorado, eastern Utah and the Four Corners region -- where Arizona, Colorado, New Mexico and Utah intersect -- received 20 percent to 50 percent of average precipitation. Now, dry conditions are spreading into other parts of the region: Last week, much of the basin saw less than one-tenth of an inch of rain.

During the webinar, analysts expanded the area categorized as experiencing severe or extreme drought to cover much of western Colorado, eastern Utah and a small portion of southern Wyoming.

The region's rivers and reservoirs aren't faring very well, either. The snowpack that accumulates in the region's mountain ranges over the winter -- which becomes the water supply for the upper basin when it melts over the spring and summer -- is already almost gone, according to the assessment.

"Snowpack conditions around the Upper Colorado River Basin are all well below average and many sites have completely melted out," the report says.

That's due to a combination of below-average snowpack last winter and "much earlier" melting, the assessment says. For example, runoff in the Gunnison Basin in western Colorado peaked about a month earlier than usual -- and that's fairly typical for sub-basins throughout the region.

As of June 10, 87 percent of U.S. Geological Survey stream gauges in the Upper Colorado River Basin recorded stream flows that were below normal. Only the Upper Green River is seeing near-normal flows.

As a result, many of the region's reservoirs, which usually swell this time of year, instead are seeing levels drop. Two reservoirs -- McPhee in Colorado and Flaming Gorge in Wyoming -- are above average, while the rest in the Upper Colorado River Basin are below their June averages. Lake Powell, one of the largest reservoirs on the Colorado River, which provides water for millions of people, sits at 64 percent of "full pool."

Conditions are so dry that farmers have had to plant fewer crops and ranchers are shrinking their herds, officials with the U.S. Department of Agriculture's Farm Service Agency said.

"It's very dry here. We've heard of ranchers liquidating their cattle," said Janice Wallace of FSA's Arapahoe County, Colo., office. "You walk out on the pastures, and it just crunches under your feet."

Groundwater is more scarce, too, added Mike Blair, FSA's district director for northeast Colorado. "With irrigation, we've had reports of some poor or lower-producing wells that normally would produce around 600 gallons a minute being down to about 300 gallons a minute," he said. "The aquifer is being drawn down more quickly this year."

Click here to see the assessment.

Reese writes from Santa Fe, N.M.