December was an unsettled and very wet month, a fitting end to the third wettest year (after 2000 and 2012) for the UK in a series from 1910. Rainfall was above average across the majority of the UK, exceptionally so across East Anglia and north-east Scotland (recording their wettest and second wettest Decembers since 1929, respectively). River flows generally far exceeded December averages across England and Wales, notably so in south Wales and eastern and south‑western England, and exceptionally so in East Anglia where flows were two to three times the average. Soil moisture deficits were near-zero across the whole of the UK, the wettest soils for late December at a national scale since 2012 and comparable with 2000. Groundwater levels rose and were in the normal range or above, with some exceptionally high levels. Reservoir stocks in December were above average at a national scale, notably so in Yorkshire, south-west England and Northern Ireland. Saturated soils across the country and high river flows and groundwater levels imply an elevated risk that rainfall will bring fluvial and groundwater flooding episodes through the remainder of the winter.