WASHINGTON, Aug 9: US scientists say July was the hottest month ever recorded in the Lower 48 states, breaking a record set during the Dust Bowl of the 1930s. They say climate change is a factor.     And even less a surprise: The US this year keeps setting records for weather extremes, based on the precise calculations that include drought, heavy rainfall, unusual temperatures, and storms.    

The average temperature last month was 77.6 degrees (25 Celsius). That breaks the old record from July 1936 by 0.2 degree, according to the National Oceanic and Atmospheric Administration.

Records go back to 1895.    ''It's a pretty significant increase over the last record,” said climate scientist Jake Crouch of NOAA's National Climatic Data Centre In the past, sceptics of global warming have pointed to the Dust Bowl to argue that recent heat is not unprecedented.

But Crouch said this shows that the current year “is out and beyond those Dust Bowl years. We're rivalling and beating them consistently from month to month.''

Three of the nation's five hottest months on record have been recent Julys: This year, 2011 and 2006. Julys in 1936 and 1934 round out the top five.    Last month also was 3.3 degrees (1.7 Celsius) warmer than the 20th century average for July.

Thirty-two states had months that were among their 10 warmest Julys, but only one, Virginia, had the hottest July on record.

Crouch said that's a bit unusual, but that it shows the breadth of the heat and associated drought.

For example in 2011, the heat seemed to be centered mostly in Oklahoma and Texas. But this summer “the epicenters of the heat kind of migrated around. It kind of got everybody in the action this month,” Crouch said.

The first seven months of 2012 were the warmest on record for the nation. And August 2011 through July this year was the warmest 12-month period on record, just beating out the July 2011-June 2012 time period.

But it's not just the heat that's noteworthy.—AP