Irish Weather Statistics

I still need to look at what you want Artane2002. As a finishing post today, I'll do this quick one on 1st July 1997. An unusually cold mid-Summer's day!

A northerly airstream took place on this day carrying with it some very cold air including the 0c isotherm touching the northwest of Ireland - like late Winter to early Spring styled temperatures at 850hPa. This was a very odd day to have in what was otherwise a warm month and a warm Summer.

At several stations, it was their coldest July day on record including the following with their maximum temperature recordings on the 1st.

Casement Aerodrome - 10.6c (previous record: 13.0c on 2nd July 1974)
Clones - 10.7c (previous record: 11.7c on 2nd July 1974)
Dublin Airport - 11.7c (previous record: 12.2c on 5th July 1954)
Kilkenny - 12.3c (previous record: 12.5c on 13th July 1980)
Malin Head - 10.2c (previous record: 11.4c on 5th July 1978)
Mullingar - 10.9c (previous record: 11.3c on 2nd July 1974)





Data comes from Met Éireann.

How unusual are cold and dry Summers (these two elements combined)? A Winter counterpart to this question is how unusual are mild and dry Winters? The simple answer is, they're rare and very strange seasons. I just wanted to incorporate mild and dry Winters into this equation too because they're equally as odd as cold and dry Summers.

Our climate is designed to give us mild and wet Winters along with coolish to rather mild and wet Summers. However, as with any climate, there are always exceptions to the "rule". These exceptions are done by pattern changes to the normality. To have a mild and dry Winter, we must have a strong Polar Vortex up to the north but with high pressure building over us from the Azores. Low pressure must lie way to the north than to the northwest to bring the dry weather. But if it doesn't, then you have our typical zonal setup. This is the kind of setup you want in Summer, not Winter! Years this has happened include 2016-17 and 1991-92 as recent examples. In this sort of setup, it tends to be very dull and very boring with little to no variety in weather. 1991-92 was the dullest Winter on record in some parts with less than 100 hours of sunshine all season and for some of those, it was also the driest Winter on record. December 1991 was the worst of them all with more than 75% of the days being sunless for the majority of stations but it was also the driest December on record.

Here's an example from December 1991 of this setup:



Meanwhile, to get a cold and dry Summer, high pressure must be out in the Atlantic ridging in across Ireland sending the jet stream over to the east of the UK but still on a north or northwest to southeast trajectory. The high over Ireland means that we're blocking off the Atlantic from throwing depressions at us. With the north or northwesterly winds, it means we're dragging cold air from the north but the low pressure is being sent to the east of the UK and into Scandinavia. This has occurred in Summer 2011, 1981 and 1972 in recent times. Summer 2011 had high pressure more out into the Atlantic and over Greenland than near us but nevertheless, it was dry for a lot of Irish stations but very cool! Like the mild and dry Winter setup however, this cool and dry setup for Summer is not good at all for sunshine. Summer 2011 was the dullest on record in parts before Summer 2015 & 2016 came. Summer 1981 was the dullest on record for parts too though for others not as dull as Summer 1980. Summer 1972 I think was very dull too and included the coldest June of the 20th century.

Here's an example from July 1981 of this setup:



I chose Valentia Observatory for an example of Summer 1981's stats because it is the wettest synoptic station on average in Ireland. Notice the lack of 10mm+ days in July and the dry periods/interludes in June and August. But also look at the temperatures, it didn't really warm up 'til the latter part of July and August. To you, that may look wet because you live in Dublin, the driest county on average in Ireland. However, remember that this is Valentia Observatory we're looking at which is the total opposite to Dublin and is in Co. Kerry.



So yes, very unusual and gladly so!

UK's lowest air maximum temperatures for each month:

Month|Record|Date|Location
Jan|-13.0|10 Jan 1982|West Linton
Feb|-10.0|9 Feb 1895 / 1 Feb 1956|Braemar / Princetown
Mar|-4.7|1 Mar 2018|Tredegar
Apr|-1.1|1 Apr 1917|Durham & Macclesfield
May|1.6|1 May 1979|Knockanrock
Jun|5.1|2 Jun 1975|Nunraw Abbey
Jul|7.5|5 Jul 1978|Clashnoir
Aug|8.9|27, 28 Aug 1919 / 18 Aug 1964|Ampleforth, Bradford & Newton Rigg / Lerwick|
Sep|4.4|29 Sep 1915|Braemar
Oct|0.4|17 Oct 1973|Glenmore Lodge
Nov|-10.5|29 Nov 1985|Kinbrace
Dec|-15.9|29 Dec 1995|Fyvie Castle


- The symbol "&" on this table notes two or more stations recording a record on the same day. For example, Bradford & Newton Rigg both recorded an air maximum of 8.9c on 28th August 1919.
- Altnaharra nearly equalled the December record with an air maximum of -15.8c on 22nd December 2010.

Remember that the Irish record is -9.8c at Cavan on 21st December 2010.

Data comes from the UK Met Office.

Here's how the Mays have fared in the 21st century so far for your interest Artane2002 (including 2000 even though it's not technically part of the 21st century).

2000 - Very sunny. Dry start but becoming wet.
2001 - Very warm and sunny. Mostly dry especially in the south.
2002 - Exceptionally wet and dull. Close to average temperatures. Record breaking rainfall on May 17th for parts of the east.
2003 - Rather wet and dull. Becoming warmer towards the end.
2004 - Dry, mild and sunny.
2005 - Fairly cool, wet and sunny.
2006 - Wettest May on record in places but sunny and mild.
2007 - Sunny and warm. Mostly dry but wet to the north.
2008 - Warmest May on record. Very sunny and dry.
2009 - Very warm and sunny but wet.
2010 - Becoming warm after a cool start. Very sunny and dry.
2011 - Fairly mild though that was down to largely warm nights. Days were mostly cool. Wet and mostly sunny.
2012 - Cold during much of the month but a very warm spell near the end. Rather sunny and variable rainfall - wet in the east.
2013 - Cold, wet and dull.
2014 - Very dull, wet and mild. Dullest on record for some.
2015 - Very wet, cold and dull. This was the poorest May in my opinion.
2016 - Warm, sunny and close to average rainfall.
2017 - Very warm, sunny and dry.

nacho libre wrote: »

I can remember the wet summer of 1986 you wrote about earlier. I recall my father and a neighbour complaining about not being able to get square bales done all summer. It seemed to nearly rain every day and it was often cold like you mentioned.

Summer 1986 may have had a memorable June with some great thunderstorms but it deteriorated fast with one of the dullest Julys on record and one of the wettest and coldest Augusts on record. That August broke the Irish daily rainfall record twice subsequently!

Even the worst of Summers can have their moments, 1962 being an example. This Summer failed to reach 30c in the UK and it followed the coldest March of the 20th century with a notable spell of cold and snowy weather at the end of February into the start of March - then this was followed by the Winter of 1962-63 . In fact, the maximum temperature for the entire year in the UK was 27.8c at Writtle, Essex. This equalled with 1928 for the lowest annual maximum temperature for the UK of the 20th century. Want to know something even stranger about it? It was recorded on the 3rd September 1962, not even during the meteorological Summer season.

Here's a quick RTÉ Archive video/report on the 5th June 1962 when the warm weather brought Dubliners to Seapoint to take advantage of some of the only warmth they would receive for the entire Summer and year:

http://www.rte.ie/archives/2017/0522/876991-sunshine-at-seapoint-on-dublin-bay/



Maximum temperatures for a few stations for the period 4-9 June 1962:

Station|4 Jun|5 Jun|6 Jun|7 Jun|8 Jun|9 Jun
Dublin Airport|16.4|15.6|18.3|20.1|21.3|18.3
Kilkenny|18.3|17.8|19.8|21.0|23.2|18.9
Valentia Observatory|18.9|20.6|20.7|20.6|21.6|15.6
Rosslare|15.0|14.9|16.4|17.3|20.9|18.9
Birr|18.5|18.4|19.4|22.2|23.3|16.2


Data comes from Met Éireann.

Looks like a very nice short period of weather, quite ideal for me.

20 years ago, Ireland had its warmest February on record in 1998. The IMT for this month was a staggering 7.9c which is +2.6c above the 1981-2010 average. It was the warmest February on record at every station in Ireland including the long-term stations of Valentia Observatory, Malin Head and Phoenix Park. For the CET, it was 7.3c which made it the equal warmest February of the 20th century with 1990 here. The values this month brought were more typical of April than February. The month had a north-south split in terms of rainfall in both the UK and Ireland. The south had a very dry month with it being the driest February since 1986 but the north had a relatively wet month. Sunshine was very variable. The majority had a dull month but parts of the southeast of Ireland and much of the south of the UK had a sunny month. In southeastern England, it was the sunniest February of the 20th century - in spite of being such a warm month. Very strange for Winter!

The 13th February 1998 was an especially incredible day in the UK. This day produced the February record with a maximum temperature of 19.7c at Greenwich, London in blue skies! Other remarkable temperature recordings in the UK included 19.6c at Worcester on the 13th, 19.1c at Tivington on the 14th and 18.1c at Prestatyn on the 15th. It was so warm and sunny you could go to the beach, a bit awkward to be doing in Winter. A maximum of at least 13c was exceeded somewhere in the UK every day from the 8th to the 20th February 1998. A maximum of at least 13c was recorded somewhere in Ireland every day from the 8th to the 15th February 1998. When it's mild like this in Winter, it's normally dull with a long fetched southwesterly flow. However, this was one of those rare exceptions where the Winter warmth was associated with sunshine. The maximum temperature for Ireland this month was set two days after on the 15th with 17.3c at Phoenix Park in relatively sunny skies. Not quite the Irish record of 18.1c set at the same station on February 23rd 1891 but still remarkable nonetheless especially in the sun. The majority of stations had no air frost at all from the 4th-26th February 1998.

See the synoptics for 13th February 1998 with the +8c isotherm making it up as far as north Scotland.







Here's some more maxima from 13th February in the UK:

Aberdeen: 15.8C
Bedford: 17C
Belfast: 14.9C
Birmingham Airport: 16C
Cardiff Airport: 14C
Coventry Airport: 16C
Glasgow Airport: 14.3C
Gravesend-Broadness: 19C
Hawarden: 17.3C
Liverpool Airport: 16C
London Weather Centre: 19.1C
London Gatwick: 17C
London Heathrow: 18.6C
Manchester Airport: 16.5C
Northolt: 18.7C
Nottingham: 17C
Pershore: 16.9C
Rhyl: 14.5C

All data comes from the UK Met Office or Met Éireann.

**Easter 1998 was colder than anything February delivered that year. You've seen the disaster that Easter 1998 was in my recent analysis on it. And no, there was no SSW. The culprit was the very strong El Nino. The top 6 strongest El Ninos were all followed by cold Aprils. Each very strong El Nino has produced significant Winter warmth at some stage. 1877-78: very mild February. 1982-83: very mild January. 1997-98: very warm February and even some record breaking warmth in January. 2015-16: phenomenally warm December.**

Newspapers were as stupid in 1998 as they are today:

"Records melted by February heatwave"

https://www.independent.co.uk/news/records-melted-by-february-heatwave-1144560.html

https://twitter.com/metoffice/status/985171577447899136

I've been wanting to do this post for a while now and this is on August 1947. You already know of the big freeze of 1947 followed by the wettest March on record with severe floods. August 1947 was the fourth hottest August on record for the CET (not just of the 20th century but all-time) with a mean temperature of 18.6c. This made it the hottest month of the 20th century up to that point. August 1995 in comparison had a CET of 19.2c. I do not have the IMT figure for August 1947 but the IMT for August 1995 was 18.2c. If I were to estimate, August 1947 would be around 17.8c for the IMT. For the synoptic stations' data available for this month, one of them recorded heatwave conditions and this station was Shannon Airport with a length of 7 consecutive days having a maximum of at least 25c or above. It was exceptionally dry with it being the second driest of the century behind only 1995 and not surprisingly, very sunny too! 1947 was certainly not a year without interest, it's the ideal year for a lot of weather enthusiasts as it had blizzards, severe cold, floods and a heatwave.

Professor Trevor Harley's description on the month for the UK:

August. Very hot (18.6) and dry; no rain at all around Glasgow and Aberdeen, Borrowdale (Lake District) and parts of eastern England (e.g. Boston, Lincoln). Even the Isle of Skye (August average 125mm) only had 5mm. On average England and Wales had only 17% of the long-term average. It was the warmest August of the century for some places (such as Scotland), the driest in many places, and the sunniest, with an average of 10-11 hours of sun per day. Unsettled start. 34C in Bournemouth on the 16th. One thunderstorm, on the 23rd, at Sudbury, with 84mm. This was clearly the best summer month of the century so far.

There have been several attempts of creating an index for showing how good a Summer was in Ireland. One example was the "Summer Index" (innovative name ) by N. E. Davis which used the formula:

I = T + 2s - 2.5r

where T = mean daily maximum temperature in Fahrenheit
S = mean daily sunshine in hours
R = mean daily rainfall in mm

Using this formula and Armagh Observatory's (which has records going back to 1794 and sunshine data goes back to May 1880) statistics, August 1947 was the best month from 1880-1979. You can find the best months using the index below during the period 1880-1979 at the observatory.

Rank|Month|Index
1|August 1947|88.5
2|August 1976|86.2
3|June 1940|84.5
4|June 1949|83.6
5|July 1955|82.5
6|August 1899|81.7
7|June 1957|81.3
8|June 1921|80.7
9|June 1895|80.6
10|June 1975|80.4
11|July 1934|80.4
12|June 1889|80.2
13|August 1880|79.9
14|June 1925|79.3
15|June 1930|78.9
16|June 1932|78.7
17|May 1896|78.4
18|August 1911|78.3
19|July 1977|78.2
20|June 1939|78.1


The reanalysis for August 1947 really gives away why it was such a scorcher of a month with a big block over us and to the northeast drawing in a hot easterly to southeasterly flow.



The daily CETs for August 1947 were:

Date|CET
1|19.1
2|19.8
3|18.4
4|17.3
5|16.6
6|15.9
7|15.4
8|14.8
9|16.1
10|17.9
11|17.3
12|18.1
13|19.7
14|19.3
15|20.4
16|21.6
17|22.0
18|22.1
19|20.9
20|20.0
21|20.1
22|20.0
23|19.1
24|17.6
25|17.3
26|18.8
27|18.7
28|19.4
29|18.6
30|17.1
31|16.9


The mean CET maximum for August 16th 1947 was 29.2c. To compare with the hottest day of this decade so far, July 19th 2006 had a daily CET maximum of 32.9c.

Here are some of the stations' maximum temperatures for August 1947

Date|Shannon Airport|Valentia Observatory|Dublin Airport
1|23.3|19.7|21.7
2|21.7|19.4|17.9
3|20.9|19.3|19.1
4|20.7|19.5|16.6
5|19.2|16.4|19.1
6|18.9|17.2|17.7
7|17.9|18.3|15.7
8|21.1|18.8|17.8
9|21.5|16.8|18.5
10|18.5|16.2|21.6
11|20.6|17.8|21.0
12|23.8|21.1|21.4
13|23.7|18.6|21.0
14|26.1|26.1|22.1
15|27.5|28.1|22.8
16|28.7|24.3|23.0
17|28.4|23.3|21.6
18|26.8|21.7|20.4
19|26.2|19.1|24.0
20|27.9|26.7|20.1
21|24.1|25.2|20.2
22|25.7|21.7|19.8
23|18.9|18.3|20.2
24|24.1|21.1|17.8
25|23.8|22.2|20.4
26|25.1|23.9|20.3
27|25.6|24.2|20.8
28|26.2|26.6|22.7
29|26.3|26.1|23.3
30|24.0|22.8|22.6
31|24.1|22.6|19.4


Precipitation totals (mm) for August 1947 at these stations

Shannon Airport|Valentia Observatory|Dublin Airport
22.8|24.7|32.7


*Dublin Airport had a downpour of 23.8mm on August 2nd 1947 but had only 0.1mm of rain from the 7th to the 31st. Shannon Airport had 20.5mm on the same day with 1.1mm of rain from the 7th to the 31st.



From 15 August 1947 issue of the Ballymena Observer:



Sources

http://climate.arm.ac.uk/scans/1947/08/INDEXA.html
http://adsabs.harvard.edu/full/1980IrAJ...14..165M
http://www.met.ie/climate-request/
http://www.trevorharley.com/weather_web_pages/1947_weather.htm
https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/m/e/aug1947.pdf