WASHINGTON (Reuters) - Hotter-than-normal temperatures are expected through October over most of the contiguous 48 U.S. states, with below-average precipitation for Midwest areas already hit by the worst drought in a half century, government forecasters said on Thursday.
Experts at the National Oceanic and Atmospheric Administration did not rule out drought that could continue past October, and they noted that there was a chance of an El Nino pattern that could mean more excessive heat and dry conditions by the end of 2012.
After the hottest half-year on record in the United States, hotter, drier conditions from the Southwest, through the Midwest and across the East Coast from Florida to Maine are forecast to continue through October, the National Oceanic and Atmospheric Administration said at a briefing.
Drought hit 29 U.S. states, with Texas feeling the heaviest impact, followed by Colorado, Missouri, Florida, New Mexico, Arkansas, Indiana and Hawaii.
Nationally, last month was the 14th warmest June on record, with 170 temperature records broken or tied. Only the Pacific Northwest had near-average temperatures.
The record-high temperatures were unusual for June; record-breaking heat more frequently occurs later in the summer, according to Jake Crouch of NOAA's National Climatic Data Center.
More than 53 percent of the area of all of the United States -- including Alaska, Hawaii and Puerto Rico -- was experiencing moderate or worse drought this week, according to the latest U.S. Drought Monitor released Thursday.
That set a record for the third consecutive week, making it the most widespread drought in the 12 years the government has been mapping this data. Drought conditions last week extended to 50.92 percent of the U.S. area, compared to 53.17 percent this week, said Kelly Helm Smith of the National Drought Mitigation Center.
"We don't have a reason for saying it's going to improve," Smith said, acknowledging that warmer conditions in the coming months might well exceed current levels, with potentially tough impact on agriculture.
Another gauge of U.S. drought distress came in the form of voluntary reports, which rose from fewer than 50 in January to over 300 in the first half of July.
Smith included one such report from an unnamed farmer and rancher in Colorado: "With record-setting high temps. and several days of 108 to 113 degree temps, irrigation water shutting off and the dry hot wind, conditions of pasture have turned from bad to worse. Ranchers are now calling in with reports of finding dead antelope fawns in the shade of cedar posts, very sad situation. Cattle are starting to go to town."
A La Nina pattern of cool water in the equatorial Pacific, which normally brings colder, wetter conditions to parts of the continental United States, ended earlier this year, and there is a good chance that an El Nino pattern could develop before year's end, said Dan Collins of NOAA's Climate Prediction Center.
That could prolong drought conditions in the central United States, Collins said.
"There's a greater chance that there is no relief possible or in sight" for the U.S. Midwest, Collins said, stressing that these are probabilities, not definitive predictions.
Another reason drought may be extended is that extreme heat seen across much of the country has depleted moisture in the soil, which means there is less moisture to evaporate and fuel precipitation.
Around the world, last month was the fourth-warmest June. Temperatures on land were the warmest ever recorded, while ocean temperatures were the 10th warmest. The Northern Hemisphere had its second-warmest June on record.
The United Kingdom had its coolest June since 1991, while Austria had the sixth-warmest June in 250 years.
Reporting by Deborah Zabarenko; Editing by Dale Hudson and Cynthia Osterman