The past 12 months were the second wettest on record in the UK, according to data released by the Met Office.
The total rainfall for the UK during 2012 was 1,330.7mm (52.4in), just 6.6mm short of the record set in 2000.
Most areas were affected by the extreme weather, with thousands of homes flooded and farmers struggling to grow crops in the saturated soil.
The latest data comes as analysis says the frequency of extreme rainfall in the UK may be increasing.
BBC environment analyst Roger Harrabin said statistics showed that days of particularly heavy rainfall had become more common since 1960.
The study into extreme rain was based on statistics from the National Climate Information Centre, the UK's official climate record.
The Met Office said this was the wettest year on record for England, the third wettest for Wales, the 17th wettest on record for Scotland and the 40th wettest for Northern Ireland.
The records date back to 1910.
The Met Office added that four of the top five wettest years had occurred since 2000.
"The trend towards more extreme rainfall events is one we are seeing around the world, in countries such as India and China, and now potentially here in the UK," said Met Office chief scientist Prof Julia Slingo.
"Much more research is needed to understand more about the causes and potential implications."
Most areas in the UK experienced flooding during 2012, affecting thousands of homes and businesses.
In the run-up to Christmas, South-West England was particularly badly affected, with a number of railway lines remaining closed over the entire festive period.
The Environment Agency said almost 8,000 properties in England and Wales were flooded during 2012 and it sent more than 200,000 warnings to households and businesses.
However, it added that flood defences had protected more than 200,000 properties in at-risk areas.
The rural economy was hardest hit by the poor weather, explained National Farmers Union (NFU) president Peter Kendall.
"The NFU estimates the appalling weather of 2012 has led to a financial black hole on Britain's farms amounting to a staggering £1.3 billion," he said.
"As we enter 2013, many farmers are in areas under water or facing a double-whammy of huge feed bills for their livestock."
According to insurer NFU Mutual, weather-related claims from farmers were expected to exceed £108 million but if the cost of reduced yields and failed harvests was also included then the final bill would be much higher.
Country Land and Business Association president Harry Cotterell said: "Farmers have lost valuable crops to the freak weather, which has had a knock-on impact for consumers as prices rise and produce becomes scarce and of poor quality."
The end of the year was in stark contrast to the beginning of 2012 when politicians, farmers and water industry officials held a "water summit" to look at supply concerns.
Areas in southern and South-East England were experiencing very low groundwater levels, prompting a number of water companies to impose hosepipe bans.
Institution of Civil Engineers Water Panel chairman Michael Norton said now was an ideal time to look at how the UK manages its water resources, in times of drought as well as during flooding events.
"The management of drought and flooding are interdependent and require a coherent strategy," he explained.
"Without a strategy, we will continue to swing from flooding to drought and climate change will only exacerbate the situation.
"There are many measures that can help us manage water more effectively from multipurpose reservoirs, storage ponds for agriculture, sustainable urban drainage systems, and household rainwater harvesting.
"But this requires a strategy bringing in all of the key players involved in water resource management and usage."
Mr Norton called on the government to establish a "UK Water Security Task Force" to provide the necessary leadership to deliver long-term water security.