"However mean temperature is still expected to be significantly warmer than in 2000, when a similar strength La Nina pegged temperatures to 0.24 degree C above the 1961-90 average. Sharply renewed warming is likely once La Nina declines," he added.
The current La Nina is now the strongest since 1999-2000. The lag between La Nina and the full global surface temperature response means that the cooling effect is expected to be a little greater in 2008 than it was during 2007.
The World Meteorological Organisation said last month there were indications that the 10 years from 1998 to 2007 were the hottest decade on record.
The Met Office Hadley Centre said the top 11 warmest years have all occurred in the last 13.