1995 had already been a vintage year for weather extremes in the UK and Ireland with an exceptionally wet and mild Winter, two notable tornadoes in March (including one in Meath on St. Patrick's Day), an extremely dry April, a Summer of droughts and heatwaves including two official heatwaves and the hottest month on record for Ireland (August 1995), a very warm Autumn (warmest on record for some at the time) and Winter 1995-96 was to start off similarly extreme.
Much of December 1995 had been mixed with changeable air masses. For example, Belmullet recorded a maximum temperature of 14.0c on the 3rd which became its highest temperature for December on record though this has since been beaten by 4 dates (see below).
Top 5 highest December temperatures on record at Belmullet.
Shannon Airport had a maximum of 15.0c on the 2nd, the highest temperature of the month. These mild conditions were down to southerly winds. Both days were very mild in Ireland with maxima widely between 13-15c. Notice the intense blocking over Scandinavia though.
The winds turned easterly on the 4th and resulted in outbreaks of hail, rain and snow showers. Snow was mainly on high ground in Ireland but it fell on some lower levels, mainly in the UK. Maximum temperatures by the 6th for some were only around 2 or 3c - remember it had been over 10c warmer than that just a few days before it. It was very sunny out west but damp and cold in the east due to the easterly wind.
The easterly got cut off for a time around the start of the second week but high pressure remained influential and by the 13th/14th, this high retrogressed setting up this block shown below. These were all signals that the atmosphere was acting very abnormal. The winds became increasingly easterly and cold air started to infiltrate into the east again resulting in mainly rain showers with snow on higher ground in Wicklow.
On the 19th, a Greenland High tried to set up and the winds attempted to go to a northerly but you can see a deep area of low pressure in the North Atlantic about ready to push up from the south to affect Ireland. In fact it did, the south had some very wet conditions from the 19th to 21st including a daily rainfall of 36.8mm at Cork Airport on the 19th.
Northerly to easterly winds continued to have a fight at pushing the low back southwards on the 20th resulting in a chilly day for the north of the country but again cloudy and wet further south. The low made its way northwards to all on the 21st reintroducing milder air for all parts. Further very wet conditions on both the 21st and 22nd.
Low pressure cleared to the east on the 23rd and allowed a northeasterly flow to take over. This caused conditions to become increasingly cold again and frost getting more severe each day.
The wind veered northerly on Christmas Eve and a trough developed within the cold air resulting in snow showers for some in the north and northwest. Maximum temperatures by this stage widely between 3-6c and minimum temperatures overnight going below freezing. Fairly gusty northerly winds with a 54 knot gust at Malin Head on this day.
The unstable northerly flow continued into Christmas Day with a White Christmas for a good few places including stations like Clones and Dublin Airport. Variable sunny spells. Maximum temperatures were below freezing for the majority of the day in the north midlands with an afternoon maximum of 0.7c at Clones. Severe frost overnight with more than 90% of the country recording air frost including -5.4c at Birr. It was the second of three White Christmasses in the 90s for Ireland - the other two being 1993 and 1999.
Winds became lighter on the 26th (as shown by the isobars below becoming less closely packed and more open) resulting in freezing fog over the midlands and more severe frost again. Snow showers continued in the north. Clones recorded an air minimum of -7.1c early on the 26th. Plenty of sunshine away from the midlands to be enjoyed.
The northerly winds remained light on the 27th to 29th before veering easterly and strengthening on the 30th as low pressure approached from the south giving away to some instances of freezing rain especially over the southwest of the UK. Clones recorded an air minimum of -11.0c on the 27th, its lowest for December on record and Letterkenny (Magherenan) recorded -13.3c on the 28th, also its lowest for December on record and any month since its records began in 1978. The latter value was the lowest December temperature in Ireland since 1961 and the lowest temperature for any month since January 1982.
Records were set in the UK. On the 29th, Fyvie Castle in Aberdeenshire, Scotland recorded a maximum of only -15.9c which was the lowest maximum temperature on record for any month in the UK and 22 December 2010 came close at Altnaharra with a maximum of -15.8c. Altnaharra observed a minimum temperature of -27.2c on the morning of the 30th making it the joint lowest temperature on record of all-time for the UK - other days it was recorded being 11 February 1895 and 10 January 1982. This also made it the lowest December temperature on record for the UK beating the previous record of -26.7c on 3rd December 1879.
Lowest temperatures for selected Irish stations during the spell.
Due to the frequent easterly and northerly winds, it ended up as the sunniest December on record (until 2010) in parts of the northwest including Belmullet. Was similar in some ways to the December 2000 cold spell although the December 1995 cold spell was more potent in Britain due to the lighter winds overall.