The averaging period used for the following assessment was 1981-2010.
December started mild and changeable with westerly winds, and this pattern continued until the 9th, but there was a cold snap, mainly in the north, between the 3rd and 6th. A Scandinavian blocking high brought a colder quieter spell between the 10th and 14th, especially to eastern parts. Storm Deirdre brought widespread freezing rain on the 15th, which caused considerable travel disruption. The mild changeable weather type returned from the 16th to 23rd. From the 24th onwards it was somewhat more settled with high pressure dominant. A generally westerly flow resulted in mild and mostly cloudy weather, but parts of eastern Scotland and north-east England saw a fair amount of sunshine.
The provisional UK mean temperature was 5.8 °C, which is 1.9 °C above the 1981-2010 long-term average. Mean maximum temperatures were generally 2 °C above average in England, Wales and Northern Ireland, and 1.5 °C above in Scotland. Mean minimum temperatures ranged from 3 °C above average in parts of Wales and south-west England to less than 1.5 °C above in the north and east of Scotland and parts of north-east England. Rainfall was 99% of average and sunshine was 92% of average. It was a dry month in the north and east of Scotland and in north-east England, but elsewhere rainfall was near or above average. Sunshine was above normal in eastern Scotland and north-east England, but well below normal in the west, and parts of Northern Ireland, Wales and the West Country had less than half the normal amount.
The UK monthly extremes were as follows: A maximum temperature of 15.9 °C was recorded at Kew Gardens (London) on the 2nd. A minimum temperature of -8.8 °C was recorded at Braemar (Aberdeenshire) on the 5th. In the 24 hours ending at 0900 GMT on the 8th, 64.6 mm of rain fell at Cluanie Inn (Ross & Cromarty). A wind gust of 71 knots (82 mph) was recorded at sle of Portland (Dorset) on the 8th. A snow depth of 1 cm was measured at Bowhill (Selkirkshire), Tulloch Bridge (Inverness) and Gartocharn (Dunbartonshire) on the16th.
Icy conditions caused a few road traffic accidents in Scotland during the mornings of Monday 3rd and Tuesday 4th December. Some travel disruption was reported from localised flooding in parts of south and southwest Wales on 5th December. A low pressure system to the north of the UK brought strong winds to Scotland, Northern England, North Wales and Northern Ireland on 7th December. In Scotland, a number of roads were closed with restrictions on the Queensferry and Forth Bridges. Several schools were closed in the Western Isles and in Northern Ireland the Rathlin Island Ferry was cancelled. Further strong winds on 8th December across south-west Engand resulted in road closures, and in Cornwall there were reports of trees bringing down power lines resulting in around 100 homes losing electricity for a time.
Storm Deirdre on 15 to 16 December brought freezing rain, snow and ice to northern parts of the UK. In Northern Ireland a number of roads were blocked due to flood water, and in Wales, there were reports of fallen trees blocking roads and bringing down power cables, with flooding on roads also causing road closures. Across southwest England there were reports of flooding on numerous roads with Cross Country rail services reportedly cancelled or restricted.
Further north, icy conditions led to a number of road traffic accidents. Scotrail reportedly cancelled some services between Perth and Inverness, the Tay Road Bridge was closed to high sided vehicles with reports of fallen trees on numerous roads in Scotland. Snow reportedly caused travel disruption with reports of HGVs becoming stuck. Up to 15,000 homes were left without power across Scotland with widespread freezing rain. Across the north of England a number of roads were closed to prevent vehicle becoming stranded due to black ice. There were reports of a number of road accidents, also some reports of fallen trees and flooding causing travel delays. Some roads were reported as impassable. Northern Powergrid reportedly restored power to 20,000 customers. In south Yorkshire it was reported that two women died in a traffic accident during hazardous driving conditions.
On 17 to 18 December, further wind and rain affected Northern Ireland, Wales and southwest England. There were reports of numerous trees obstructing roads, with flooding also causing disruption to road travel. In Wales, there were reports of power cuts, flooding causing road closures and disruption to the rail line between Mountain Ash and Aberdare.
The weather was generally quiet toward the end of the month, with high pressure dominating. Fog caused some problems across Northern Ireland and the Glasgow area in the run-up to Christmas, and more widely across England from Christmas Eve into Christmas Day.
England diary of highlights
The first third of December was generally mild, wet and windy. It turned more settled and briefly colder around midmonth due to a Scandinavian blocking high, and widespread freezing rain in central and northern counties caused disruption on the 15th, but mild wet weather returned from the 17th to 23rd. From the 24th onwards it was somewhat quieter with high pressure dominant. A mild westerly flow maintained generally mild cloudy weather during this period, but it was often sunny to the east of the Pennines.
The mean temperature for December was provisionally 2.2 °C above the 1981-2010 long-term average, and it was the joint 5th mildest December in a series from 1910, although it was not as warm as December 2015. It was a dry sunny month in the north-east, but elsewhere rainfall was near or above average, and it was very dull in the south-west with less than half the normal sunshine amount over much of Cornwall. Overall England had 96% of average sunshine and 115% of average rainfall.
1st to 4th
It was generally mild, wet and windy with westerly winds. The 1st was a mild cloudy day with some rain especially for the north and near the south coast, and the 2nd continued mild, generally cloudy and windy with some light rain in many places in the afternoon, with a maximum of 15.9 °C at Kew Gardens (London). The night of the 2nd/3rd was unusually warm with Swanage (Dorset) not falling below 12.6 °C. Colder, drier and sunnier weather spread into the north on the 3rd, while rain spread eastwards through the Midlands and East Anglia with showery weather further west and south. A ridge of high pressure led to a frosty start for many on the 4th and it remained cold in the north with a high of only 1.2 °C but milder cloudy weather spread into the south and rain reached the south-west during the afternoon.
5th to 10th
The 5th was another mild wet day, particularly over the north and west, and rain spread to most parts from the south-west by evening. The rain was mostly light and patchy on the 6th, then a band of locally heavy rain moved eastwards on the night of the 6th/7th, clearing eastern counties on the 7th with sunshine and showers following from the west. Showers and longer spells of rain spread from west to east on the 8th and it was very windy in the south with gusts to 82 mph at Isle of Portland (Dorset). The 9th was less mild, particularly in the north, with some sunshine but cloudier weather and showers affected most areas from the Midlands southwards. A ridge of high pressure brought a mostly sunny day to eastern areas on the 10th but it was cloudier in the west with some showers feeding through the Cheshire Gap.
11th to 16th
This period saw a persistent blocking high over Scandinavia, but this gave only a brief cold snap. The 11th continued sunny and quite cold in the east and mild and cloudy in the west, and this weather pattern persisted on the 12th and 13th also, with some rain for the south-west. Fog was slow to clear in the Midlands on the 11th, and East Malling (Kent) recorded 7.0 hours of bright sunshine on the 13th. The 14th started off clear and very cold in central and southern parts with a minimum of -6.6 °C in South Farnborough (Hampshire), and some showers affected eastern coastal counties, while patchy rain headed into the south-west by evening. Storm Deirdre brought strong winds on the 15th and widespread freezing rain from the Midlands northwards with sleet and snow also reported in some places, and Shap (Cumbria) collected 38.6 mm. Most places started off bright on the 16th but rain spread to western, central and southern counties by evening.
17th to 23rd
Mild changeable weather returned during this period, with some some patchy rain spreading into the south-west on the 17th following a dry bright start. The 18th was a generally wet and windy day, followed by a bright day for most on the 19th with a few showers in the west and south, mainly in coastal areas, although cloud and rain was slow to clear in parts of eastern England. Some light rain affected central and northern counties on the 21st, then the 22nd was a mostly bright mild day but with showers for the north and west. A slow-moving area of rain affected parts of the Midlands, north and south-west on the 23rd.
24th to 31st
High pressure dominated the weather and a westerly flow on its northern flank kept the weather generally mild and cloudy, but to the east of the Pennines it was often relatively sunny. The 24th was mild and drizzly in the south-west, brighter with near-average temperatures elsewhere and some lingering fog patches across eastern counties. The milder cloudier weather spread to most parts on the 25th and persisted until the 27th, but it remained brighter in the north-east, with some mist and fog patches in the east, and parts of the south-west were sunny on the 27th. The 28th was cloudy in the south-east but brighter elsewhere with some mist and fog patches in central areas. The 29th started windy in the north, with cloud clearing eastwards followed by generally brighter weather, sunniest in the north-east. The 30th and 31st were generally mild and cloudy, with a little light rain in the north on both mornings which died away.
Wales diary of highlights
Mild cloudy weather prevailed for much of the month, with generally changeable and windy weather until the 23rd and then mostly quiet anticyclonic weather from the 24th onwards. There was a brief cold snap midmonth which gave widespread freezing rain on the 15th.
The mean temperature for December was provisionally 2.5 °C above the long-term average, and the positive anomaly was much larger by night than by day. It was the joint 5th mildest December in a series from 1910. Rainfall was 121% of average and sunshine was just 48% of average, and it was a particularly dull month in the south-west. For Wales as a whole it was the dullest December in a series from 1929.
1st to 9th
This period was generally mild and wet with westerly winds. The 1st was mild and also wet at times, then the 2nd was brighter but with some light rain or showers during the afternoon. Rhyl (Clwyd) reached 14.8 °C on the 2nd, and then the night of the 2nd/3rd was unusually warm with Milford Haven (Dyfed) not falling below 11.2 °C. Rain cleared away on the 3rd followed by drier brighter weather, then a ridge of high pressure brought a bright frosty start to the 4th before cloudier weather spread from the west, with rain into the south-west by evening. The 5th and 6th were mild and wet, with 47.2 mm at Capel Curig (Gwynedd) on the 6th, though the heavy persistent rain cleared from late morning on the 6th. Rain cleared on the morning of the 7th followed by sunshine and scattered showers, and there were showers and longer spells of rain on the 8th. The 9th had a mix of sunshine and showers.
10th to 15th
A Scandinavian blocking high brought only a brief interruption to the mild cloudy weather during this period. The 10th had a ridge of high pressure but it was generally cloudy and mild with some light drizzle. There was some patchy fog in the north on the 11th until mid-morning, otherwise it was another grey drizzly mild day. The 12th and 13th were both cloudy, with some rain along the west coast, but the cloud broke up in many areas on the afternoon of the 13th. This led to a frosty night on the 13th/14th with Mona (Anglesey) falling to -4.1 °C early on the 14th, and there was a maximum of just 0.8 °C at Llangunllo (Powys), but the 14th was also a relatively sunny day with 5.0 hours recorded at Hawarden (Clwyd). Storm Deirdre brought windy weather on the 15th combined with rain, sleet and widespread freezing rain.
16th to 23rd
Mild and changeable weather re-established during this period. The 16th and 17th both started off dry and bright before rain spread from the west. The 18th was a wet and windy day, and gusts reached 79 mph at Aberdaron (Gwynedd), followed by a day of sunshine and scattered showers on the 19th, the majority of the showers in the west. The 20th was generally cloudier with further showers, and there were some longer outbreaks of rain on the 21st. The 22nd was a brighter day with a few showers, but cloudy wet weather returned on the 23rd.
24th to 31st
This period was more settled with high pressure close by, but a generally westerly airflow maintained mild cloudy weather. The 24th was a sunny day in the north-east with 5.0 hours recorded at Colwyn Bay (Clwyd), but it was cloudy and drizzly in the south and south-west. The cloudy drizzly weather spread across the country for the 25th, with a maximum temperature of 11.7 °C at Gogerddan (Ceredigion). The 26th to 28th remained mild and cloudy although there were some sunny intervals in the far south on the 27th. The 29th had some rain for central and northern parts early in the day, turning drier and brighter into the afternoon, but the 30th and 31st were again cloudy and dry.
Scotland diary of highlights
The first third of the month was often mild and changeable but with some colder snaps. It turned more settled but generally cloudy from the 10th to 14th, and Storm Deirdre brought widespread freezing rain on the 15th. A week of changeable weather and variable temperatures followed. The last week was generally dry with some sunny spells in the east but cloudy with rain at times in the west, and it was often very mild.
The mean temperature for December was provisionally 1.4 °C above the 1981-2010 long-term average. Rainfall was mostly near or below average, but it was above average in parts of the Western Isles. Sunshine was mostly above normal in central and eastern parts but below normal in the west. Overall, Scotland had 80% of average rainfall and 106% of average sunshine.
1st to 9th
It was changeable during this period with variable temperatures. The 1st was generally cloudy with some rain in the south and showers in the north-west. Some central and northern parts had a frost early on the 2nd, with some light rain in the south and heavier rain spreading eastwards across the north. A northerly outbreak on the 3rd brought a mostly sunny day with showers across the far north, and this introduced a cold snap. There was a widespread frost early on the 4th followed by a bright cold day with some showers in the south, and in the far north where some of them were wintry. Braemar (Aberdeenshire) fell to -8.8 °C early on the 5th, and the 5th was another cold bright day in the north but it turned milder in southern and central parts with rain spreading from the west. Milder air set in on the 6th with rain clearing eastwards followed by some bright spells and scattered showers, these mainly for the north and west. The 7th was a sunny day in the east and south but stormy with showers and longer spells of rain over the north and west, with 64.6 mm at Cluanie Inn (Ross & Cromarty). The south had a longer spell of rain on the 8th and was generally dry and sunny on the 9th, while the north had sunshine and showers on both days, and it turned colder on the 9th.
10th to 16th
A Scandinavian blocking high brought a spell of colder quieter weather. The 10th was a cold bright day in the east, cloudier and milder in the west, with rain spreading to western coastal areas after midday, and on the 11th and 12th cloudy weather spread to all parts, with light rain in the west. The 13th was colder, with further rain in the far west and also some showers in the east, while staying cloudy, and the 14th was similar, but some clear spells in central and southern parts resulted in a widespread frost early on the 14th. Storm Deirdre brought wet and windy weather from the west on the 15th, which turned widely to freezing rain, also with sleet and snow in some places. 1 cm of lying snow was recorded at Bowhill (Selkirkshire), Tulloch Bridge (Invernesshire) and Gartocharn (Dunbartonshire) on the 16th, followed by a brighter day but with rain showers in the west.
17th to 22nd
Fog was slow to clear in the south on the 17th, then mild and windy weather established with rain reaching the west coast late in the afternoon and there was a high of 14.0 °C at Plockton (Ross & Cromarty). The 18th was very windy with gusts of 81 mph at South Uist (Western Isles), and rain, locally heavy, spread from the west to all parts, followed by showers from the west late in the day. The 19th was mostly sunny with just a few showers over the west and south. Showers were more widespread on the 20th but it stayed mainly dry and bright in the north-east. The 21st was a cold day for many with a maximum of only -0.4 °C at Cromdale (Morayshire), with showers for the north and south but it was mainly sunny in the east, and the 22nd was showery in the west but sunny in the east.
23rd to 31st
This period was more settled in the east with high pressure close to the south, but more changeable in the west, and it was generally mild. The 23rd was mainly dry and sunny with a few scattered showers across the north-west Highlands and Aberdeenshire. The 24th was rather cold in central and eastern areas, and mainly cloudy and dry with some lingering fog patches in central and eastern areas, but Baintown (Fife) recorded 6.3 hours of bright sunshine. The 25th was mainly cloudy but with a few brighter intervals mainly in eastern areas, and some light rain or drizzle affected the west. The night of the 25th/26th was very mild with a minimum of 10.0 °C at Aultbea (Ross & Cromarty), and on the 26th rain and drizzle became heavier and more persistent in the north-west. The rain and drizzle eased again in the west on the 27th, while some sunny intervals developed in the east but most places stayed cloudy. Overnight rain cleared eastwards early on the 28th followed by a mainly sunny day. A further band of rain and strong winds crossed the country early on the 29th and showers lingered near northern and eastern coasts, but otherwise it became mostly dry. The 30th and 31st were generally cloudy and very mild, with some rain in the north-west, but the 31st had some sunny spells in the north-east. The temperature fell no lower than 10.0 °C at Kinloss (Morayshire) on the night of the 30th/31st.
Northern Ireland diary of highlights
The weather was mostly mild and changeable and dominated by westerly winds until the 23rd, but with a brief colder spell between the 13th and 16th. The last week was quieter with high pressure close by, but a generally westerly flow kept the weather very mild and cloudy with occasional drizzle.
The month’s mean temperature was provisionally 2.0 °C above the 1981-2010 long-term average. Rainfall was near average for most of Northern Ireland, and sunshine was below average, especially in the west where there was less than half the normal amount. Overall rainfall was 96% of average and sunshine was 61% of average, and it was the third dullest December in a series from 1929.
1st to 12th
This period was generally mild and changeable. The 1st was generally wet, and rain spread to all parts from the west on the 2nd after a bright start. The 3rd was a brighter day with scattered showers, and Katesbridge (County Down) recorded 5.3 hours of sunshine. With a ridge of high pressure and clearing skies, Katesbridge (County Down) also fell to -4.1 °C early on the 4th, but it turned cloudier from the west on the 4th. Rain cleared north-eastwards on the 5th followed by sunshine and showers, then the 6th was cloudy with some light rain. A showery spell followed between the 7th and 9th, with some longer spells of rain on the 8th but also some sunshine in between the showers. Between the 10th and 12th Northern Ireland was in a mild southerly airflow and it was generally mild and cloudy with some light rain or drizzle, and on the 12th light rain especially affected the east.
13th to 23rd
It turned colder on the 13th with widespread rain, turning a little drier in the afternoon, and a narrow band of rain moved eastwards through the country on the afternoon of the 14th. Storm Deirdre brought wet and windy weather on the 15th with 45.4 mm at Ballypatrick (County Antrim). The 16th was a brighter day while continuing quite cold with a maximum of only 4.1 °C at Lough Fea (Londonderry). Outbreaks of rain spread from the west on the 17th, when it also turned much milder and very windy. Gusts reached 64 mph at Magilligan (County Londonderry) and Orlock Head (Down) early on the 18th, but the rain cleared eastwards followed by sunshine and showers. The 19th was a bright day with just a few scattered showers, but it was cloudier with showers and longer spells of rain on the 20th and 21st. The 22nd was a brighter showery day, then the 23rd was mainly cloudy with some intermittent rain in the south.
24th to 31st
High pressure brought quieter weather during this period but with a generally westerly airflow it was generally cloudy, damp and mild. The 24th started cold, sunny and frosty but cloud and light rain spread from the west. The 25th to 27th were mainly cloudy with a little light rain or drizzle, but Trassey Slievenaman (County Down) reached 13.1 °C on the 25th and some sunny intervals developed in the far south-east on the 27th. The 28th was a brighter day, but cloudy weather returned between the 29th and 31st, with some light rain in the west on the 29th. Under cloudy skies the nights were particularly mild, and Armagh and Killowen (both County Down) did not fall below 9.7 °C overnight 30th/31st.