By Richard Black
Environment correspondent, BBC News
The government hopes the project will lead to better protective measures such as sea walls
Detailed forecasts of how climate change may affect the UK during this century are to be released by the government later.
The report will predict how temperature and rainfall are likely to change at regional and local scales.
Scientists believe winters will be wetter, particularly in the north, and summers drier, especially in the south.
The projected impacts are "worse than the government had feared," according to a source familiar with the project.
The government hopes the UK Climate Projections 2009 report (UKCP09) will allow citizens, local authorities and businesses to plan better for future decades.
Using a range of online tools including a "weather generator", people will be able to enter their postcodes and see projections of how conditions are likely to change within 25 sq km grid squares at different points in the future.
"[This is] the most comprehensive set of probabilistic climate projections at the regional scale compiled anywhere in the world," said John Mitchell, director of climate science at the UK Met Office, which has taken charge of the computer modelling of climate used in the report.
The previous report - UKCIP2002 - is now seven years old, and included projections from just one computer model.
By contrast, UKCP09 has collated data from 400 variations of the model developed by the Hadley Centre, part of the Met Office.
Each variant has been checked to see how well it predicted the climate of past decades; and the numbers have been compared with projections of other computer models.
This allowed scientists to assign probabilities to various forecasts.
The idea of the impact assessment has been well received by environment groups.
"It's great that the government has decided to put together such a scientifically robust analysis of the potential impacts of climate change in the UK, but the picture it paints is an alarming one," said Keith Allott, head of climate change at WWF-UK.
"This research confirms that not only is climate change already having a serious impact in Britain, but that we are also locked into further impacts, and that these impacts will get much worse unless we act now to tackle the problem."
Campaigners say that the UK impacts are likely to be minor compared to other parts of the world.
Last month a report from the Global Humanitarian Forum, the think tank chaired by former UN secretary-general Kofi Annan, said that the UK was among the 12 countries likely to be least affected by climate change.
On Friday, the Environment Agency will release an assessment of how the changing climate will affect the risk of impacts such as flooding in England and Wales.