Montthly Weatther
Summary
The Weather of December 2006
Mild and wet; sunnies
st in no
orth and eas
st
December was a month of contrasting weather types, as wet and windy weather during the first half of the
month was replaced by much calmer conditions with little rainfall, but with widespread frost and fog at
times. Late in the month, unsettled but very mild conditions returned. The early part of December was
dominated by deep Atlantic depressions to the northwest of Ireland, bringing spells of heavy rain at times;
following the very wet second half of November, there was significant river flooding in some midland and
western areas. Rainfall totals for the month were above normal everywhere and were significantly above
normal in parts of the midlands, west and north. It was the wettest December for 6 or 7 years generally.
There were between 15 and 23 wetdays (days with 1mm or more rainfall) during the month, slightly above
the normal range for December. Most of the month was mild, but temperatures fell close to or below
normal during the spell of calmer weather between the 15th and 25th. Air frost was mostly confined to the
period between the 19th and 23rd; the total of between 3 and 5 air frosts at inland stations was only around
half of the normal number for December, while there was no air frost recorded at most coastal stations.
Sunshine totals varied widely across the country; Dublin Airport’s total of 69 hours was more than twice the
amount recorded in parts of the west.
1st to 17th: A series of very deep depressions passing to the northwest of Ireland brought rain or showers each day,
accompanied by strong southwesterly winds. Heaviest falls were recorded in the periods 2nd to 4th and 13th to 15th;
close to 100mm of rain was measured in places in the 5-day period between November 30th and December 4th,
causing some significant flooding. Further disruption was caused by very strong winds at times, with gale gusts at all
stations between the 1st and 3rd and also on the 7th and 13th. Thunder was frequent early in the period.
Temperatures were near or above normal throughout, while many days during the period were dull.
18th to 26th: An intense anticyclone drifted slowly eastwards across Ireland to become centred over southern
England for much of the period. This period was dry apart from some light showers in places, but very light winds
allowed fog to become dense and widespread between the 18th and 20th. Daytime temperatures fell below normal,
especially in areas where fog was persistent, while ground frost was widespread up to the 23rd. Much of the period
was dull, but there were long sunny spells at first in some areas where fog cleared during daylight hours.
27th to 31st: As the anticyclone moved away eastwards, Atlantic depressions again moved close to the northwest
coast, bringing a return to wet and windy conditions over Ireland. Heaviest falls were in southern and western areas.
Strong to gale force southerly winds brought very mild air across all parts of the country.
Wind and elements: Mean windspeeds for the month were between 9 and 13 knots generally (17 and 24km/hour)
and up to 18 knots (33km/hour) in the north and northwest. These were the highest mean winds for December since
1999. The highest gust of the month, 79 knots (146 km/hour), was measured at Malin Head on the 31st, its highest
December gust since 1998. Both hail and thunder were recorded on several days during the first half of the month,
especially in the periods 1st to 3rd and 8th to 12th; they were also recorded in the period 29th to 31st. Most unusually
for December, there was no snow observed at any station. Fog, with freezing fog in places, was very widespread
between the 18th and 20th.
Extreme values
Rainfall
Highest total: 227mm at Valentia Observatory (its wettest December since 1999)
Lowest total: 95mm at Dublin Airport
Highest daily rainfall: 34.8mm at Belmullet on 29th (its highest December value since 1992)
Temperature Highest mean monthly temperature: 9.2°C at Valentia Observatory
Lowest mean monthly temperature: 5.3°C at Knock Airport
Highest temperature: 14.5°C at Casement Aerodrome on 14th (its highest December value since 1994)
Lowest air temperature: -4.3°C at Mullingar on 23rd
Lowest grass minimum temperature: -8.9°C at Kilkenny on 22nd
Sunshine
Highest monthly total: 69 hours at Dublin Airport
Lowest monthly total: 29 hours at Knock Airport (its dullest December since records began there in 1996)
Highest daily sunshine: 6.6 hours at several stations
December 2006
Daily values at selected synoptic stations
Rainfall (mm)
28
25
20
15
10
5
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Sunshine (hours)
7
6
5
4
3
2
1
0
1
2
3
4
5
6
Maximum temperature (°C)
15
10
5
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Minimum temperature (°C)
15
10
5
0
-5
5
1
2
3
4
5
6
7
8
z Valentia Observatory
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
- Dublin Airport
„
Clones
December 2006 Percentage / Difference from 1961-90 monthly normals
Rainfall
(% of normal for period 1961-1990)
Belmullet
205
175
Birr
146
Casement Aero
161
Claremorris
150
Clones
Cork Airport
133
Kilkenny
133
178
Malin Head
173
Mullingar
145
Rosslare
168
Shannon Airport
143
Valentia Observatory
75
100
125
Temperature
150
175
200
225
(°C difference from normal for period 1961-1990)
Belmullet
1.3
Birr
1.3
1.5
Casement Aero
1.2
Claremorris
1.2
Clones
0.8
Cork Airport
1.1
Kilkenny
0.9
Malin Head
1.1
Mullingar
1.3
Rosslare
1.2
Shannon Airport
1.6
Valentia Observatory
-0.5
0
Sunshine
Belmullet
0.5
1
1.5
2
(% of normal for period 1961-1990)
97
109
Birr
139
Casement Aero
109
Clones
91
Cork Airport
117
Kilkenny
171
Malin Head
106
Mullingar
122
Rosslare
99
Shannon Airport
98
Valentia Observatory
75
100
125
150
175
200