The first nine months, January to September, tied with 2003 as the seventh warmest such period on record, with a global land and ocean surface temperature of about 0.48 degree Celsius above the 1961–1990 average. (Agencies)
January-September 2013 was warmer than the same period in both 2011 and 2012, when La Nina had a cooling influence.
Neither La Nina nor El Nino conditions were present during the first nine months of 2013 and are not expected to emerge by the end of the year.
El Nino/La Nina is a major driver of our climate and the hottest years on record, 2010 and 1998, both had El Nino events.
"The year 2013 is currently on course to be among the top ten warmest years since modern records began in 1850," WMO said.
In contrast with 2012, when the US, in particular, observed record high annual temperatures, the warmth in 2013 was most extreme in Australia, the statement said.
"Temperatures so far this year are about the same as the average during 2001-2010, which was the warmest decade on record," said WMO Secretary-General Michel Jarraud.
"All of the warmest years have been since 1998 and this year once again continues the underlying, long-term trend. The coldest years now are warmer than the hottest years before 1998," he said.
The provisional WMO statement confirms that global sea level reached a new record high. Sea level has been rising at an average rate of about 3.2 millimeters per year (mm/yr), with inter-annual variability, since altimeter satellite measurements began in 1993.
This is close to the observed rate of about 3 mm/yr of the most recent decade of 2001-2010 and double the observed 20th century trend of 1.6 mm/yr.
In Asia, Japan had its hottest summer on record. China recorded its warmest August on record (tied with 2006). South Korea observed its 4th warmest July and warmest August, contributing to a record-high summer temperature.
Large areas in south west Asia including India, Pakistan, and western China experienced above-average rainfall due to the active Southwest Asian monsoon, which was one of the longest on record, the organization said.
The monsoon season had an early onset and brought the worst flooding and devastation in the past half century to regions near the India-Nepal border.
The North Indian Ocean had a below-average season with only two tropical cyclones compared with the 1981-2010 average of four. Phailin evolved into the strongest storm in the North Indian basin since 1999.
The first nine months, January to September, tied with 2003 as the seventh warmest such period on record, with a global land and ocean surface temperature of about 0.48 degree Celsius above the 1961–1990 average.