The records set were:
:: All-time high of 38.7C (101.7F) on 25 July in Cambridge
:: Winter high of 21.2C (70.2F) on 26 February in Kew Gardens in London - a few days after 20C was recorded during winter for the first time
:: December high of 18.7C (65.7F), three days after Christmas in Achfary, Sutherland
:: New mildest daily temperature for February, when it didn't go below 13.9C (57F) in Achnagart in the Highlands, on the 23rd
The records are detailed in the latest annual State of the UK Climate report, by The Royal Meteorological Society.
It also says 2019 was the 12th warmest year in the UK since 1884 - but the 10 warmest years have all been since 2002.
The most recent decade (2010-2019) was on average 0.9C warmer than 1961-1990, and 0.3C warmer than 1981-2010.
No cold temperature records were set last year.
As well as the temperate records, 2019 also saw the worst flooding for four years, as South Yorkshire, Derbyshire, Nottinghamshire and Lincolnshire were badly hit in November.
"Our report shows climate change is exerting an increasing impact on the UK's climate," said lead author and Met Office climate information scientist Mike Kendon.
"This year was warmer than any other year in the UK between 1884 and 1990, and since 2002 we have seen the warmest 10 years in the series.
"By contrast, to find a year in the coldest 10 we have to go back to 1963 - over 50 years ago."
Dr Mark McCarthy, head of the Met Office's national climate information centre, said: "The climate statistics over time reveal an undeniable warming trend for the UK.
"We are also reporting on changes in other aspects of our weather and environment, such as rainfall, snow, sunshine, sea level and even tree leafing dates.
"The observed changes are to varying degrees a consequence of both global climate change and natural variability in our climate."
The mild February also saw the first leaves appearing on trees nearly 10 days earlier than the 1999-2018 baseline, according to the Woodland Trust.
Chief executive Darren Moorcroft said: "Whilst this may not sound like much, research using these citizen science records has shown this can have dire impacts further down the food chain.
"Our trees, and all the wildlife they support, are on the front line of climate change and ultimately some species will be able to adapt better than others.
"This is a stark reminder of the need to take immediate action on climate change."