Summary

  • Temperature-  overall mean (CET for England); rather above average (+1.5C)
  • UK rainfall –  rather above average (120% of the average)
  • UK sunshine – rather below average (85% of the average)
  • Winds- rather above average strength & predominantly likely to be W-SW’ly

December forecast synoptic summary

Week 1 from the 1st-7th December will initially see high pressure across France but low pressure to the NW  and a southerly flow developing on the 3rd though low pressure running across the south and works away SE on the 4th with pressure rising from the west but further deep low pressure will be near Iceland giving a stronger gradient across the UK. Another low seems likely to run NE from the Atlantic towards N Ireland & W Scotland by late on the 5th, and further deep low pressure areas running across NW of Scotland allowing some colder shots of PM air into the north but staying mainly milder in the south.

In week 2, from the 8th-14th December an unsettled chilly W-NW'ly flow will likely dominate across the north with a deep Atlantic low well to the north of Scotland but high pressure may become more dominant to the south or SE by the 8th and ridge NW towards Iceland but then as it moves away east allow a milder TM S'ly flow to run north across all parts on the 10th. Around the 12/13th, there may be a change to a more westerly flow with polar air running east into the north & west.

From the 15th- 21st it is very difficult to pin down the likely synoptic patterning though it seems most likely that low pressure still looks set to dominate the Atlantic, developing in & running from east from the central Atlantic on a strong jet up towards Scandinavia whilst high pressure lies across central Europe or Iberia leaving the UK in a generally SW or westerly flow between the two systems.

By the last quintile of December we have low confidence but it seems likely that high pressure will remain most dominant in the south & east but that  low pressure to the west will bring fronts across the north and west with incursions of tropical and polar maritime air in equal measure.

 

December forecast weekly weather summary

Week 1 from the 1st-7th December will initially see a mild SW'ly flow across the UK  with high pressure across France, bringing rain to the NW & rather mild temperatures to some eastern parts. By early on the 2nd some gales affecting the far NW and a band of rain working SE across central parts but it should remain mild in the south and fairly dry. A ridge of high pressure develops across the north and colder in the far north on the 3rd with some wintry showers but elsewhere a mild southerly flow continues as the slow moving rain band affects central & southern parts into the 4th with a weak low pressure running across the south and giving some heavier rain at times but with colder air still affecting the far north with some wintry showers. The rain band finally works away SE late on the 4th but the gradient strengthens in the north again due to deep low pressure near Iceland and severe gales are likely to affect Scotland again with further rain sweeping SE; the stronger gradient working SE too on the 5th, bringing stronger winds into the south & west again. It seems likely at the moment that another low will run NE from the Atlantic towards Ireland by early on the 6th, bringing further gales in the west  and a lot of rain in the south & west, it'll stay very mild in the south though with the risk of hill snow in the Highlands. The week probably ending windy but mild in the south & west but staying cooler in the north as another deep low pressure area runs across to the NW and further fronts & rain work into the north & west; it may become colder from the west later with wintry showers in the north.

Generally, temperatures will be well above average for most in the south & east esp by night. The far north will be somewhat closer to average. Rainfall will be above average for most parts and very wet in the north west and west Wales but possibly a bit nearer average in the far SE and east.  Sunshine below average for most parts but perhaps a little nearer in the east and NE.

 

In week 2, from the 8th-14th December it currently looks most likely that an unsettled chilly PM W-NW'ly flow will predominate across the north as a deep Atlantic low over Norway initially dominates the UK's weather but the details are not at all clear as yet in such a changeable period, and high pressure may become more dominant to the south or SE by the 8th and pressure rise to affect all southern parts and ridge up towards Iceland. It'll become fairly dry across all parts but with chilly nights in places inland but still mild in the SW. By the 10th a breezy milder S'ly flow covering all parts with gales developing in the exposed west & NW. Showery rain seems likely almost anywhere in this period but it should stay mild in most parts away from the far north & NE and the east may see some sunny periods.

Towards the end of the week, probably around the 12th, a change to a more westerly flow with polar air into the north & west and becoming cooler for most with temperatures closer to average. Some showers at times, wintry over Scottish mountains with frost in sheltered parts inland at night.

Temperatures will generally be rather above average in the south & central parts but near average for most northern parts; rainfall will be generally be above average for most northern, central and western parts but probably nearer average in the NE, east and perhaps the SE as well. Sunshine probably slightly below average for most parts.

 

From the 15th-21st December it is very difficult to pin down the likely synoptic patterning after mid December in such an unsettled period, at present though it seems most likely that low pressure still looks set to dominate the Atlantic, developing in & running from east from the central Atlantic on a strong jet up towards Scandinavia whilst high pressure lies across central Europe or Iberia leaving the UK in a generally SW or westerly flow between the two systems. The west looks most likely to see unsettled weather with rain or showers whilst the east may remain drier & a little brighter after low cloud, early mist or fog slowly clears.

Temperatures are likely to be near average in the north & west, but southern & central regions may stay rather above average both by night and day. Rainfall near average generally in most eastern areas but western parts possibly above average and sunshine generally near average for most eastern & NE'ern parts though perhaps below average in the south and west.

 

By the last quintile of December we have very low confidence but it seems likely to stay rather settled in the south & east bringing some night fog and frosts, the fog or low cloud lingering by day when high pressure becomes reasonably dominant, the low pressure to the west bringing fronts across the north and west with periods of rain & showers, wintry at times over northern hills and quite breezy generally with gales in exposed western & NW'ern spots at times too.

Temperatures near average, with average or above average rainfall in the northwest but below average in the south east; slightly above average sunshine in the east but near average sunshine for most though perhaps slightly below average in the north & NW.

Sea temperatures seem likely to continue to be slightly above normal around the eastern UK coasts and rather above on the north Scottish coasts but slightly below average in the west. Soil moisture will be above average in all areas except possibly the east & SE where it'll be nearer average.

 

David Wiseman disclaimer – Issued as a non commercial  ‘Not for profit’ forecast. The user assumes the entire risk related to its use of this data. I am providing this data "as is" and disclaim any and all warranties, whether express or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose. In no event will I, David Wiseman, or any related contactors be liable to you or to any third party for any direct, indirect, incidental, consequential, special or exemplary damages or lost profit resulting from any use or misuse of this data . Climate stats have been compiled with the partial use and help of UKMO news page data , with thanks. Other news data was compiled from many sources including UKww reports, news papers & some BBC local news reports.