Provisional data indicates that it was the wettest June since 1860, a spokesman for MeteoGroup said. It was also the dullest since 1909 and the coldest since 1991.
Average rainfall over England and Wales, including an estimated figure for June 30, was 157mm – 231% of the average for the period 1981-2010, and on a par with the 1860 readings.
The equivalent figures for Scotland were 104mm and 171% of the normal amount, and for Northern Ireland 145mm and 224%.
Average sunshine over England and Wales, including an estimated figure for June 30, was 123 hours, which is a mere 64% of the 1981-2010 average, making it the dullest June since 1909.
The equivalent figures for Scotland were 123 hours and 74%, and for Northern Ireland 136 hours and 75%.
"Such monthly totals would not have been out of place in February," the spokesman said.
Daytime temperatures were typically 1.5-2.5 degrees Celsius below the long-term average in most parts of the country, and the Central England Temperature of 13.6C (56F) was 0.9 degree Celsius below the average for 1981-2010 – the lowest in June since 1991.