Republic of Ireland 2018 Summary

A wetter than average year overall despite a relatively dry start. Winter 2018-19 was generally anticyclonic after a changeable December, becoming extraordinarily mild in late February with numerous all-time records set. Spring was more mixed with an unsettled start but drier later on. Summer was unusual in being dominated by high latitude blocking but managed to be warm whilst being wet. Despite this, the summer included up to 3 exceptional heatwaves, one of which set the all-time UK record maximum temperature beating the August 2003 record. It was the warmest-wetter than average summer since records began in 1884. Autumn 2019 was very wet with the jet stream being further south than normal. The year ended on an appropriate note with a new record December maximum temperature set in Scotland but December 2019 was not as mild as December 2018. 

January. Westerlies dominated Ireland during January with a strong North Atlantic jet stream overhead. Much of the month was on the mild side (but milder Januaries have been recorded in 2012, 2014, 2016 and 2017) although the first weekend offered a dry period with the expense of low temperatures and night time frosts along with the third week characterised by episodes of cold zonality resulting in outbreaks of wintry showers including sleet and snow especially on the 16th. As you'd expect given it was a westerly month, it was wetter than average across Ireland. Malin Head (Co. Donegal) recorded 203.7mm of rainfall during January making it the wettest month here since its records began in 1885. The maximum temperature seen during January was 13.8°C at Roche's Point (Co. Cork) on the 27th whilst the minimum temperature of -6.8°C was recorded at Athenry (Co. Galway) on the 8th. Mount Dillon (Co. Roscommon) recorded a grass minimum temperature of -12.4°C on the 8th also. It was a sunnier than average month for most despite the Atlantic influence with Cork Airport (Co. Cork) having up to 126% of its average January sunshine. However, it was not as sunny as January 2010, 2011 and 2015 anywhere in the country. Storm Eleanor on the 2nd and Storm Fionn on the 16th resulted in storm force winds for the west of Ireland with the maximum wind gust during the month being 84 knots (156 km/h) at Knock Airport (Co. Mayo) during Storm Eleanor. The same station recorded the month's maximum 10-minute mean wind speed of 58 knots (107 km/h) during Storm Eleanor.

February. February was predominantly colder than average with a changeable westerly pattern. There were many outbreaks of wintry weather during the month including some frontal snow on the 5th/6th and the "Beast from the East" at the end of the month when a continental polar air mass from Europe made its way to Ireland via easterly winds resulting in significant accumulations of snow and bitterly cold temperatures on the 28th. It was a drier than average month generally except in the northwest exposed to cold zonality. Newport (Co. Mayo) had 43.1mm of rainfall on the 10th - its wettest February day since 9 February 2016. Mean temperatures were as much as -2.1°C below average at Oak Park (Co. Carlow) and Markree Castle (Co. Sligo) making it the coldest February since 2010. The maximum temperature during February was 14.3°C at Moore Park (Co. Cork) on the 19th whilst Gurteen (Co. Tipperary) got down to -5.7°C on the 28th. Gurteen (Co. Tipperary) also recorded a maximum temperature of -1.1°C on the 28th, the first ice day to occur in February anywhere in Ireland since 1991. It was also the first ice day for any month in Ireland since December 2010. It was a very sunny month with it being the sunniest February over the country since 2004. Knock Airport (Co. Mayo) - usually the dullest station in Ireland - had 94.4 hrs (157% of its average February sunshine) whilst Johnstown Castle (Co. Wexford) had up to 114.0 hrs of sunshine. This was the highest February monthly sunshine total for anywhere in Ireland since 2010. Dublin Airport (Co. Dublin) recorded 10.0 hrs on the 25th, as did Belmullet (Co. Mayo) on the 26th. This made it the sunniest February day on record at Dublin Airport (26 February 2019 would later equal this) beating the previous record of 9.8 hrs on 28th February 2004. Casement Aerodrome (Co. Dublin) observed a snow depth of 16cm at 9am on the 28th February 2018. Unlike December and January, there were no named storms during February 2018.

March. Continuing on from the exceptional cold end to February (coldest weather for so late in the season since at least 1795), March began extremely cold with all parts of Ireland having their coldest spring day on record on March 1st. Many stations did not get above freezing all day long. Cork Airport (Co. Cork) had a maximum temperature of -1.8°C on this day easily beating its previous record low max. for March of 0.9°C on 4th March 1965 (this would be beaten again the following day on 2nd March 2018 with a max. of only -0.4°C). On the same day, Cork Airport (Co. Cork) recorded a minimum temperature of -7.0°C making it the lowest March temperature on record at the station (records back to 1962) also beating -6.1°C on 2nd March 1965. During a temporary lull when the easterly winds calmed down, Durrow (Co. Laois) got down to -9.7°C - the lowest March temperature for Ireland since 1947 and any month since December 2010. The 1st and 2nd March 2018 were the only known March ice days for Ireland in the entire digital record back to 1942 although 18th March 2018 would later become another showing the extreme nature of the month's cold spells. There were further snow showers for most on the 1st March with Casement Aerodrome (Co. Dublin) observing a depth of 22cm of snow at 9am. Later that day, a depression known as Storm Emma (named by the Portuguese Met) approached from the Bay of Biscay and tracked northwards towards Ireland with its associated frontal systems during the first week. It yielded widespread snow and ice with more significant falls of snow and high drifts occurring over the south and east of Ireland from the 1st to 3rd March 2018. Drifts and depths from Storm Emma's invasion on Ireland were extreme over Co. Kildare and Co. Wexford in particular, such deep snow not seen the likes of in Ireland since January 1982. The max. snow depth observed was 69cm at Glenmacnass (Co. Wicklow) but even places like Bunclody (Co. Wexford) and Naas (Co. Kildare) recorded depths up to 45cm on the 3rd. Dunsany (Co. Meath) recorded a daily rainfall* of 53.2mm on the 2nd - *most of this was in the form of snow and is an estimated total. It became generally milder from the 4th onwards with the negative North Atlantic Oscillation (NAO) becoming western based so bringing the colder weather over to North America rather than western Europe. Along with it becoming milder, low pressure tended to dominate also with the wettest conditions tending to be in the south and east of the country. A deep depression yielded a lot of rain especially on the 14th with a strong southerly flow and a rainfall total of 90.7mm at Kilsheelan (Co. Tipperary). High pressure temporarily ridged in over Scandinavia from the 16th to the 18th bringing a return of very cold and snowy weather for some especially in the east. Vast majority of this snow melted quickly however by the end of the 18th and into the 19th but nevertheless, it provided more disruption across the country even if only briefly. Max. temperatures were again exceptionally low for the time of year with one station, Mount Russell (Co. Limerick), recording an ice day with a max of -0.1°C on the 18th. This was the record latest ice day in Ireland's history. The weather became unsettled yet again following this brief but severe cold snap including widespread air and ground frosts on the 19th and 20th. It started to cool down once more towards the very end into the beginning of April associated with a weak northeasterly flow. March was generally wetter than average across Ireland but drier in some northwestern regions where it was the driest March since 2013. Meanwhile, Johnstown Castle (Co. Wexford) had 215% of its average March rainfall at 169.8mm making it the wettest March on record here. It should be noted however that a lot of the precipitation in some eastern counties was of snow from Storm Emma. It was the coldest March since 2013 for most with mean temperatures ranging 2 to 3°C below average and at Valentia Observatory (Co. Kerry), it was the coldest March since 1962 with a mean temperature of 5.7°C. March was mostly duller than average which is no surprise given the dominant easterly flow but it was sunny in parts of the south and west. Even in the dullest areas, it was not as dull as March 2006 or March 2013. 

April. April was largely unsettled with a relatively cool beginning and end whilst a warmer period mid-month meant near normal to slightly above average temperatures overall. The maximum temperature at Knock Airport on Easter Monday (2nd April) was only 3.6°C. The first week of the month brought several periods of rain as areas of low pressure pushed northwards over the country bringing the wettest conditions chiefly to the south and east much like March. High pressure developed over Scandinavia in the second week allowing a slacker easterly flow and drier conditions but this came at the cost of it being very damp with a lot of cloud. Drizzle formed in the thickest cloud especially in the east of the country. By the 14th, a good few parts of the country had barely reached 25-30% of their average April sunshine with Knock Airport faring especially bad at only 11.7 hrs although an outage was reported at the station so this figure is unreliable. Nevertheless, even others like Cork Airport and Gurteen (Co. Tipperary) had only 20.8 hrs and 21.8 hrs respectively up to April 14th. Sunshine totals by that point of April should be at or around 65-80 hours, depending on location. An unusually deep depression with a central pressure of 943mb in the North Atlantic supposedly associated with Storm Irene named by the Portuguese Met made its way towards Ireland on the 16th/17th bringing a very wet and windy spell but this also forced a change in wind direction veering to a southerly. This meant temperatures were on the rise and would bring the warmest conditions of the year so far in the following days once the rain cleared through. Cloone Lake (Co. Kerry) recorded 95.4mm of rain on the 16th, its wettest April day since 2003. Similarly, Valentia Observatory (Co. Kerry) had 46.2mm, also its wettest April day since 2003. Phoenix Park (Co. Dublin) and Glasnevin (Co. Dublin) observed 20.0°C on the 18th and 19th respectively making both the warmest April days in Dublin since 2011 but this figure would be beaten by 20.5°C at Lullymore (Co. Kildare) on the 21st. A westerly flow re-established during the final week of the month with cooler conditions returning albeit a weak ridge from the northwest gave mainly dry and very sunny conditions for the last few days with air and ground frosts forming. It was the wettest April since 1966 at Cork Airport (Co. Cork) with a monthly rainfall total of 180.7mm whilst at Valentia Observatory (Co. Kerry), it was the wettest since 1940 with 197.9mm. Like March, most of the country had a duller than average April but the very sunny final few days brought totals up somewhat for Malin Head (Co. Donegal) and Casement Aerodrome (Co. Dublin). It was generally not as dull as April 2017 with the exception of Cork Airport (Co. Cork) where it was the dullest April since 1987 with only 104.9 hrs.

May. May was dominated by high pressure with a northerly displacement of the jet stream driving the low pressure systems away from Ireland and it was the driest May since 1991 at some stations such as Casement Aerodrome (Co. Dublin) with only 16.8mm but others like Valentia Observatory (Co. Kerry) had above average rainfall due to slow-moving fronts like those of the 11th and 20th. The first week was changeable in nature with an anticyclone laying to the south of the country. A southwesterly developed on the 4th bringing a tropical maritime airflow up across the country and this ushered in warmer conditions especially in the east. It was much cooler in the west where there was plentiful cloud. In the sunny east, temperatures responded well particularly on the 6th when Phoenix Park (Co. Dublin) reached 23.0°C making it the warmest May day in Dublin since 2010. The weather was mainly misty and drizzly further west. A changeable westerly returned from the 8th with temperatures dropping back to average values in the mid-teens or even slightly below average but more widespread sunny spells. Anticyclonic conditions occurred from the 16th-19th offering a fair amount of sunny conditions over Ireland. Temperatures were back above average by the 17th generally. A slow-moving occlusion pushed into the west on the 20th and 21st yielding the wettest period of the month for most including a daily fall of 27.5mm at Valentia Observatory (Co. Kerry) on the 20th. However, a blocking high over Scandinavia brought a slack easterly flow for the remainder of May bringing rather warm and sunny conditions but cloud was variable and the air became unstable for a time on the 26th and 27th. This would result in thundery showers to break out, especially in the south of the country where lightning was a significant feature on the 27th. Glenties Hatchery (Co. Donegal) had the highest maximum temperature of the month with 26.5°C on the 29th, this was below that of May 2017's warmest day in which Ballyshannon (Cathleen's Fall) (Co. Donegal) recorded 27.2°C. Despite this, it was still warmer than any day in Mays 2011, 2013, 2014, 2015 and 2016. It was not as warm as May 2017 generally in terms of monthly mean temperature but at Shannon Airport (Co. Clare) with a mean temperature of 13.1°C, it was the warmest May since 2008. 

June. An exceptional month by any stretch of the imagination with a warm spell at the beginning of the month continuing from the end of May and a heatwave during the final week that was to continue into July with drought conditions developing. Both spells were the result of Omega blocking near or over Ireland with only one westerly period mid-month. During the first warm spell, Shannon Airport (Co. Clare) successfully reached at least 20.0°C everyday from 23rd May to 9th June 2018 (18 consecutive days) beating the previous longest such spell at that time of year of 13 consecutive days from 28th May to 9th June 2016 - coincidentally only 2 years before. Storm Hector passed close to the northwest of Ireland on the 14th. The storm brought a max gust of 61 knots (113 km/h) and a max 10-minute mean wind speed of 48 knots (89 km/h) to Mace Head, its highest June winds since 2005. Hector generally brought the windiest June conditions seen in the country since 2015. Further frontal systems pushed in the west up to the 20th but these tended to be very weak in nature with the exception of the 19th when the northwest had a very wet day and Newport (Co. Mayo) had a daily fall of 33.2mm. There were isolated but intense thunderstorms for some during the first warm spell especially on the 1st and 8th with Mount Dillon (Co. Roscommon) observing an hourly fall of 25.5mm in one of these thunderstorms up to 1600 on the 8th and a 9 degree drop in temperature simultaneously from 25°C to 16°C. An anticyclone pushed in from the west on the 21st bringing cool nights at first and increasingly warm days with temperatures reaching 27°C by the 24th, 29°C by the 26th and exceeding 30°C on the 27th when a continental easterly airflow became established. Relative humidity associated with this easterly was generally low and at times exceptionally low, particularly on the 24th and 28th when stations were observing relative humidity below 30% or below 20%. At Phoenix Park (Co. Dublin), it was the driest June since 1941 with only 3.8mm of rain falling all month and the driest month of any kind since September 1986. It was the warmest June over Ireland since 1940 and for some, including Shannon Airport (Co. Clare), it was the warmest June on record; Shannon Airport had a mean temperature of 17.0°C during June which was 1 full degree above its previous warmest June back in 1970. There was 3 consecutive days from the 27th to 29th where somewhere in the country recorded 30.0°C or above and it was the warmest spell of June weather since at least 1995. These were the first 30°C observations anywhere in Ireland since July 2016 although more widely since July 2013. The maximum temperature recorded during June was 32.0°C at Shannon Airport (Co. Clare) on the 28th, its highest temperature since records began in 1946 and the highest temperature on record for an Irish synoptic station. It was the highest June temperature in the country since 1976 and for any month since July 2006. Ardfert (Liscahane) (Co. Kerry) recorded 31.6°C on the 27th and Shannon Airport (Co. Clare) recorded 31.1°C on the 29th. The lowest air temperature of the month was 2.1°C at Mount Dillon (Co. Roscommon) on the 22nd. Sunshine was well above normal at all stations with as much as 160% of average at Casement Aerodrome (Co. Dublin) and it was the sunniest June since 2009 generally but for others, it was the sunniest since 1940, 1957 or 1959. Johnstown Castle (Co. Wexford) recorded 279.9 hrs of sun during the month, the highest monthly sunshine total at any station since July 2013. There was no dull days (days with less than 0.5 hrs of sun) at Dublin Airport (Co. Dublin) and Johnstown Castle (Co. Wexford). Malin Head (Co. Donegal) recorded 16.5 hrs of sun on the 28th, a new daily sunshine record for Ireland. 

July. July continued the very warm weather from the end of June through the first two weeks. Many places yet again recording temperatures in the low to mid 20s, sometimes upper 20s, day after day. However, it was much cooler in the west on the 1st before a return to warmth on the 2nd and cooler in the north and east from the 11th-13th before a southerly push meant a warmer day on the 14th which was temporary as rain approached from the west on the 15th. St. Swithin's Day (15 July) brought an end to the absolute drought that began on 20 June but the dry spell and partial drought continued. The 16th-20th was largely a cloudier and cooler period although temperatures still above average at times especially in the south and not much rain at all despite there being some showers. A warm and humid southwesterly airflow became established from the 22nd filtering in warm tropical airmasses from the south Atlantic. This meant that whilst temperatures were above average, it was also often cloudy although sunny spells did show their hand in the south and east at times, particularly on the 25th. This pattern brought the warmest conditions of the summer to the east but not as warm as late June for most others or even the first week of July. Low pressure attacked from the west on the 27th as the ridge of high pressure progressed eastwards into central Europe. This brought a cooler and wetter end to July. The maximum temperature recorded during July was 29.3°C at Derrygreenagh (Co. Offaly) on the 4th whilst the lowest was 4.5°C at Mount Dillon (Co. Roscommon) on the 10th. Mean temperatures were well above average through July with anomalies as much as 2.2°C above average at Cork Airport (Co. Cork) and Oak Park (Co. Carlow) but at no station was it as warm as July 2013. All stations had below average rainfall through July but the wetter end did bring some totals closer to average despite the month opening with a drought period. Gurteen (Co. Tipperary) had only 24.1mm (36% of its average) of rainfall during July 2018.  It was the sunniest July generally since 2013 with up to 245.3 hrs at Johnstown Castle (Co. Wexford) but some northwestern stations had slightly below average sunshine. 

August. A big deterioration from the rest of the summer but not a washout month. It was relatively wet in the north and west with the south and east having drier and warmer conditions. All places seen wetter Augusts in 2012, 2014, 2015 and 2017 however. Mean temperatures were near normal overall but a south and east/north and west split was evident. It tended to be warmer than August 2017 for most. The first week of August was relatively anticyclonic in nature and warm but cooler conditions developed from the 8th with changeable weather on offer and any warmer interludes were very temporary between fronts. The highest temperature was 26.6°C at Oak Park (Co. Carlow) on the 18th as ex-subtropical storm Ernesto brought in a wave of tropical maritime air. The lowest temperature was -1.3°C at Moore Park (Co. Cork) on the 25th - the lowest in the country since 2014. All stations had below average sunshine similarly to August 2017 and it was the dullest August since 2008 with the most seen at Johnstown Castle (Co. Wexford) with 148.3 hrs (its dullest August since 2011).

September. A drier than average month on the whole but rather changeable in nature with the middle period of the month bringing the most unsettled conditions. The third week in particular brought a couple of depressions across the country associated with an active jet stream. Storm Ali brought a max gust of 79 knots (146 km/h) at Mace Head on the 19th along with a maximum 10-minute mean wind speed of 62 knots (115 km/h). The remnants of hurricane Helene pushed up from the south on the 17th and Storm Bronagh brought a wet day on the 20th. High pressure dominated the scene in the first and final weeks with only weak fronts bringing light rain at times, more especially out west. Record high mean sea level pressure was associated with this anticyclone including 1041.3 hPa at Sherkin Island (Co. Cork) and Cork Airport (Co. Cork) on the 24th - joint national September record with 11 September 2009. In the final week, nights turned notably cold for early in the season and resulted in September being quite a cold month compared to average. Anomalies from average were as much as -1.7°C at Markree Castle (Co. Sligo) with places having their coldest September since 2015 whilst Knock Airport (Co. Mayo) had its coldest on record since records began in 1997 with a mean temperature of 10.9°C. The highest temperature was 25.1°C at Phoenix Park (Co. Dublin) on the 2nd during a warm blip whilst the lowest was -2.2°C at Mount Dillon (Co. Roscommon). Mullingar (Co. Westmeath) broke its previous September record low of -0.1C (set in 1952) twice during September 2018 with -1.1°C on the 24th and again -1.6°C on the 29th.

October. The fourth consecutive drier than average October with all places having below average rainfall away from some isolated spots of Donegal, with totals as low as 29.3mm at Carrickmacross (Co. Monaghan) (only 31% of its October average). The first half tended to be more changeable than the second with the wettest period of the month being the 12th/13th when Storm Callum, the deepest Atlantic depression for so early in the season since 1979, made near landfall to the northwest of Ireland. The storm brought a maximum gust of 67 knots (124 km/h) at Belmullet (Co. Mayo) on the 12th and maximum 10-minute mean wind speed of 49 knots (124 km/h) at Sherkin Island (Co. Cork) and Belmullet (Co. Mayo) on the 11th. It was largely cooler than average (coolest October since 2012 generally) but with some interesting temperature fluctuations. The second week brought the warmest October conditions to Ireland since 2013 with Sligo Airport (Co. Sligo) observing a maximum temperature of 22.0°C on the 10th but in contrast, the final week of October brought some very cold nights similar to how September concluded. Dublin Airport (Co. Dublin) recorded an air minimum temperature of -4.7°C on the 30th, a new record low for October and more than a degree colder than the previous record set in 2010. This was the lowest October temperature for Ireland since 1993. It was a sunnier than average October everywhere with all having their sunniest since 2008 or 2010. Cork Airport had 131.2 hrs of sunshine (138% of its October average). An anticyclone during the fourth week of October brought record high mean sea level pressure including a new national October record of 1043.8 hPa at Sherkin Island (Co. Cork) on the 22nd.

November. Mainly dull and wet away from some northwestern regions. It was the mildest November since 2015 with nearly all mean temperatures above average. Glasnevin (Co. Dublin) recorded a maximum temperature of 16.6°C on the 3rd whilst the lowest temperature was -5.0°C at Mount Dillon (Co. Roscommon) on the 2nd. It was the wettest November since 2015 for most whilst it was the wettest since 2009 at Valentia Observatory (Co. Kerry) with 253.4mm (149% of average).