The world is enduring the hottest year on record, according to a US national weather analysis, causing droughts worldwide and a concern for US farmers counting on another bumper year.

For the first six months of the year, 2010 has been warmer than the first half of 1998, the previous record holder, by 0.03 degree Fahrenheit, said Jay Lawrimore, chief of climate analysis at the federal National Climatic Data Center.

Period of a El Nino weather pattern is being blamed for the hot temperatures globally.

'We had an El Nino episode in the early part of the year that's now faded but that has contributed to the warmth not only in equatorial Pacific but also contributed to anomalously warm global temperatures as well,' Lawrimore said.

Abnormally warm temperatures have been registered in large parts of Canada, Africa, tropical oceans and parts of the Middle East.

Northern Thailand is struggling through the worst drought in 20 years, while Israel is in the middle of the longest and most severe drought since 1920s. In Britain, this year has been the driest since 1929.

Also, Arctic sea ice has melted to its thinnest state in June.

However, as cooler temperatures may set in later this year, it remains to be seen whether 2010 will overtake 2005 as the hottest year overall.

'This year the fact that the El Nino episode has ended and is likely to transition into La Nina, which has a cooling influence on the global average temperature, it's possible that we will not end up with the warmest year as a whole.'

The record-warm weather globally hasn't translated into the same in the United States, where June was only eighth hottest to date. 'For the US, January to June, this is only slightly warmer than average,' Lawrimore said.

What may tip the scale is the development of La Nina, possibly coming in July and August, according to the National Oceanic and Atmospheric Administration.

Although La Nina means cooling globally, the transition commonly brings hotter and drier weather to the farming belt of the U.S. Midwest region.

'It's going to be pretty warm across eastern Nebraska, Iowa, western portions of Missouri, mid to upper 90s (F),' said Donald Keeney, senior agriculture meteorologist with Cropcast Ag Services.

The hot temperatures may especially hurt corn pollination, while dry weather could affect soy bean crops, Keeney said.

But meteorologist with the US Department of Agriculture Eric Luebehusen said the impact of La Nina is usually delayed for the United States, meaning good news for corn farmers.

'Most crops are already reproductive,' he said, 'so if you can last through the next few weeks, you will pass the really dangerous point where you may sustain yield losses due to heat.'

Drought is developing in some parts of the Mid-Atlantic states, Lawrimore said, but for now it's moderate and contained in eight per cent of the country. For comparison, 15 per cent of the contiguous United States was in drought last year at this time, 27 per cent in 2008 and almost half in 2007.-Reuters