December began with a cold snap: there was even an ‘ice day’ on 2nd, when the temperature never rose above freezing all day. However, the warm, wet and windy theme soon kicked back in with a vengeance, so much so that the overall mean temperature for the month, 7.4℃, made it the warmest December in our 39 years of records. The average daily minimum (5.1℃) and the average daily maximum (9.5℃) were both equal record highs too.

And it kept on raining too! It rained on 20 days, which is only slightly above average, and the maximum daily rain was 14.8, again only slightly above average, but on the days it rained it tended to really rain, so the month’s total of 92.8mm was 157% of our average December rainfall, making this our sixth wettest December.

There were several named storms crossing the UK during December: Storms Elin and Fergus on 9th and 10th, then Pia on 21st, and finally Gerrit on 27th. These kept the weather wet and windy, but the centres of the storms passed well to the north of Epping and so they weren’t too disruptive for us. There were however other depressions that didn’t make it to ‘storm’ status which did pass closer, notably one that dampened the revellers on New Year’s Eve and blew away their fireworks; that one gave us the lowest pressure of the month, and at 985.0 hPa it was third lowest for December in our more limited records of 13 years of detailed pressure readings.

However, both named and unnamed storms delivered plenty of windy weather, culminating in the strongest gust of the month of 33mph (Force 7) from the south-west on 27th courtesy of Storm Gerrit. Unsurprisingly with these low pressure systems dominating our main wind directions were from the westerly hemisphere.

Measure	Unit	Minimum	Average	Maximum	Average min	Average max	Total
Relative humidity	%	67	88	96
Temperature	°C	-3.6	7.4	14.2	5.1	9.5
Wind source (most common/highest gust)	Sector		N	SW
Wind speed	mph		4.2	33		21.3
Rain daily accumulation	mm		3.0	14.8			92.8
Barometric pressure	hPa	985	1009.9	1038.8
Solar irradiance during daylight	W/m²		51	283		153
Sunshine (sunny if irradiance > 120 W/m2)	Hours		0.7	3.5			22

Will the new year deliver more wet and mild weather, or will Winter exert its influence? Come back in a month’s time and see how the weather panned out. We will also publish a post summarising the overall weather for 2023 shortly.