I am going to be posting about October 1993 here.
October 1993 was the second consecutive notably colder than average October at the time following on from the very cold October 1992 which was the coldest in Ireland since 1981 which may not seem that notable at first sight. We have not seen any October to be as cold as 1992 or 1993 since. 1992 was more about the persistence of lower than average daily temperatures whilst 1993 produced some notable severe frosts mid-month and some of the lowest October temperatures since 1926.
The month started off on the unsettled side but it was not your average unsettled period following on from a very wet September in the south and east of Ireland. Through early October, low pressure systems tended to progress in the same regions resulting in an unusually dry month to the north and west.
This 500mb height synoptic on 5th October 1993 is indicative of the unsettled period up to the 9th. An evident anticyclone is to the southeast of Greenland with low pressure centered over southern Ireland with northeasterly winds on the northern flank of the low. It was very wet at times in the east and south particularly on the 4th-6th; some daily falls at synoptic and climate stations below:
Warrenstown, Co. Meath - 60.2mm on the 6th
Ardee, Co. Louth - 58.0mm on the 5th
Dublin Airport - 44.6mm on the 5th
Sherkin Island, Co. Cork - 32.1mm on the 4th
Derrygreenagh, Co. Offaly - 28.2mm on the 6th
Markree Castle, Co. Sligo in comparison had a maximum monthly fall of 10.5mm on the 3rd with the month total being 23.1mm, only 20% of its average October rainfall. Unusually, Warrenstown was the wettest station with 122.1mm during October, 142% of average; although nearly half of this fell on the 6th alone. Even Maam Valley, Co. Galway which is normally one of the wettest stations in Ireland, had only 81.3mm during October 1993.
This split in rainfall reflected the very easterly nature of October 1993.
Belmullet, Co. Mayo had the monthly absolute max for October on the 4th with 16.5C.
It became drier generally from the 10th onwards but further rain showers continued for a few days along eastern and southern coasts with northeasterly winds gusting to gale force. These showers merged to heavier and more persistent falls on the 12th/13th with the air becoming more unstable as air pressure lowers. Maximum temperatures stuck at 8-10C in eastern regions generally.
A northerly attempted to bring cold air down towards Ireland on the 13th and although it did become colder, we escaped the worst of the airmass with the -8C isotherm getting as far south as northern Scotland on the 15th. High pressure ridged in from the Atlantic on the 14th and 15th giving lots of sunshine and feeling cold with maximum temps only 8-12C. Both nights got down to at least -2C somewhere.
On the 16th, high pressure collapsed from Greenland over us so cut off the northerly flow. However, cold air has been established over Ireland from the northerly and with widespread clear skies, there was severe frosts. Plenty of crisp autumn sunshine with only a few coastal showers on the 17th in the southeast corner. The air temperature fell to -6.0C at Straide, Co. Mayo and Markree Castle on the 17th, a new October record for Straide and lowest at Markree Castle since 1926. Markree Castle recorded -6.0C on the 18th also (and -5.6C on the 16th). Meanwhile, Derrygreenagh had a grass min of -14.0C on the 16th.
Even some coastal regions got down to -1 or -2C on the 17th.
The high began to drift away on the 19th allowing milder and cloudier conditions to occur from the southwest although most had another severe frost during the morning.
A cold front spread southwards on the 20th with clearer skies returning from the north behind it. Light showery rain associated with the front. The severe frosts returned with sunny days for most away from the north on the 22nd and east on the 24th. Fog tended to form in the east on the 24th. Markree Castle had an air min of -4.1C on the 22nd. Days felt chilly but maximum temperatures only slightly below average or on par for late October for most in the 9-14C range.
Anticyclonic gloom for the final week of October 1993 with light easterly winds. Some brighter conditions to the south on 29th/30th. Maximum temperatures stuck at 8-11C for most under persistent cloud for days but no frost.
Data from Met Éireann.