SSEN's Weather Watch for December 2018

Heathrow temperatures - line graph

First of all, a glance at November reveals a warmer than average month, notably in Scotland with 1.3C above the 30 year average. Rainfall was close to average, but Northern Ireland recorded 130% and sunshine levels ranged between 106 and 121% of average.

November also saw a wind power record for Great Britain, reaching a peak of 12.12GW on the 28th of the month (wind power generation from wind farms which have transmission system metering installed and are visible to the National Grid).  

December’s weather patterns for the UK and Ireland look to fall into three parts, each lasting roughly 10 days. The first of these periods will bring mainly mild, wet and windy weather from the Atlantic. The windiest days are expected to be 7-8 December, when strong or gale force winds could bring gusts of 60-70mph. Outbreaks of heavy rain will accompany the gales, making for a very unsettled interlude. One or two quieter, calmer days in this 10 day period will be sunnier, but colder at night with some sub-zero temperatures.

The MetDesk map on the news summary page shows the average weather pattern for 4-8 December, featuring the westerly flow across Europe between the low pressure centred to the south west of Iceland and the high pressure established over Iberia.

The second weather regime looks set to begin on about 9 December and also last approximately 10 days. This time Europe’s weather will be influenced by an area of high pressure over Russia, which will effectively block the progress of the Atlantic weather systems. The UK and Ireland are on the border between the colder, continental air and the much milder Atlantic air, so that makes longer term predictions for us that much harder. However, a relatively cold and frosty period is likely around the middle of the month, but nothing extreme, just fairly typical for the time of year.

This temperature graph (above) for London illustrates the change with well above average temperatures for 5-8 December then slightly below average values thereafter, with the red line showing the forecast average temperature and the black line showing the climatology. 

The last week or so of the month will probably see a swing back to Atlantic weather patterns for north west Europe, bringing mostly mild, wet and windy spells of weather. Snow is only likely on the highest hills and will be transient, often turning back to rain.

We’ll be back early in the New Year to see what the weather may hold for January. In the meantime, we wish everyone a very happy Christmas and a safe and healthy 2019.

About the author

Picture of Simon Cardy

Simon Cardy Senior Meteorologist for SSE

Simon is the Senior Meteorologist at SSE and a Fellow Member of the Royal Meteorological Society. Through detailed analysis of the weather and climate, Simon provides valuable information to departments across SSE, including Networks (power distribution), Renewable Energy (wind farms and hydro dams) and Energy Demand Forecasting (how much electricity and gas we need each hour).

Read more articles by Simon Cardy