The widely anticipated UK Climate Impacts Programme (UKCIP)21st Century Climate Change Projections (2008), due about now, will not now be available until Spring 2009.
The data is crucial for all future infrastructure planning, environmental and flood defence work.
"This decision has been taken based on information provided by the Met Office Hadley Centre which needs more time to consolidate the climate projections," UKCIP has said.
"The Met Office is using ground-breaking science to produce the new climate projections – combining information from the widest possible range of global climate models. This complex process requires further analysis which will unfortunately take more time than initially expected," the organisation said.
The decision to delay the report was taken by Defra,Met Office Hadley Centre and UKCIP.