Air Temperature

Highest Maximum 18.9°C 2nd
Lowest Maximum 12.6°C 19th
Highest Minimum 14.9°C 2nd 
Lowest Minimum 6.4°C 16th

 

Mean Maximum 16.1°C
Mean Minimum 10.8°C
Mean 13.4°C

 

Relative Humidity

Lowest Relative Humidity 41% 18th

 

Mean Relative Humidity 77.5%

 

Atmospheric Pressure

Highest Atmospheric Pressure 1027.2hPa 17th
Lowest Atmospheric Pressure 1004.3hPa 6th

 

Mean Atmospheric Pressure 1017.4hPa

 

Wind

Highest Gust 66.0km/h 11th

 

Mean Wind Speed 14.4km/h
Most Frequent Wind Direction Northwest

 

Precipitation

Total Rainfall During December 2021 62.1 mm
Total Rainfall Since Last 01/09 490.2 mm

 

Highest 24 Hour Total 29.9 mm 3rd

 

Rain Days 12 days
Thunderstorm Days 1 day
Hail Days 2 days

 

Rainfall Events

02/12/2021 0.3 mm Light Rain
03/12/2021 29.9 mm Steady Rain; Distant Thunder
04/12/2021 2.4 mm Showers
05/12/2021 1.5 mm Isolated Showers
06/12/2021 4.3 mm Showers; Hail
09/12/2021 3.1 mm Isolated Showers; Hail
10/12/2021 0.3 mm Light Rain
11/12/2021 16.4 mm Intermittent Light Rain; Hail
12/12/2021 0.3 mm Light Rain
16/12/2021 2.8 mm Isolated Showers
23/12/2021 0.5 mm Light Rain
28/12/2021 0.3 mm Light Rain

 

December 2021 Compared to the Climate Means

  Climate Mean December 2021 Anomaly
Mean Maximum Temperature 17.6°C 16.1°C -1.5°C
Mean Minimum Temperature 11.8°C 10.8°C -1.0°C
Mean Temperature 14.5°C 13.4°C -1.1°C
Mean Relative Humidity 79% 77.5% -1.5%
Mean Atmospheric Pressure 1017.3hPa 1017.4hPa +0.1hPa
Mean Wind Speed 18.2 km/h 14.4 km/h -3.8km/h
Total Rainfall 109.7 mm 62.1 mm -47.6 mm
Total Rainfall Since Last 01/09 342.1 mm 490.2 mm +147.9 mm
Total Rain Days 14 days 12 days -2 days
Total Thunderstorm Days 4 days 1 day -3 days
Total Hail Days 1 day 2 days +1 day

 

The Two Faces of December 2021

The first half of December 2021 was characterized by frequent rainy episodes. Almost all of last month’s 62.1 mm of rain were measured on ten days of rain in the first half of the month. The meteorological situation changed almost like a switch midway through. The second half of December 2021 was characterized by largely dry weather conditions. This abrupt change in the meteorological situation may be attributed to the expansion of a blocking anticyclone across the western Mediterranean. This continued to expand and strengthen across mainland Europe too at the end of the month. This ensured fine weather for the Maltese Islands, as the incoming storm systems were deviated to the north. In a stark contrast to October 2021 and November 2021, last month registered just over a half of the climatic average in terms of rain.

Overall, where temperature is concerned, December 2021 turned out to be markedly colder than the climate norm. In fact, last months mean temperature of 13.4°C was a solid 1.1°C colder than that of a typical December. An episode of wintry temperatures halfway through the month contributed to this. Minimum temperatures dipped to below 10°C on a total of 13 nights. Last month’s coldest minimum of 6.4°C was  in the early hours of Thursday 16th. The coldest day overall was Sunday 19th with maximum and minimum temperatures of 12.6°C and 7.4°C respectively. Conversely, the days around Christmas and New Year’s were characterized by very warm temperatures that were advected from the Sahara Desert across to parts of the Mediterranean and western Europe.

Wind behavior also reflected the switch in atmospheric pressure patterns halfway through the month. The first half of December 2021 was notably windy, with no less than three gales being registered. The second half of last month was much calmer, as a blocking anticyclone ensured stability across the region.

 

Rainfall Totals around the Maltese Islands in December 2021 (and since last September 1st):

Għarb: 62.1 mm (490.2 mm)

Marsalforn: 49.5 mm (545.9 mm)

Victoria: 60.4 mm (503.5 mm)

Xewkija: 32.0 (468.4 mm)

Nadur: 49.8 mm (532.4 mm)

Mellieħa: 45.4 mm (476.4 mm)

Buġibba: 36.2 mm (507.9 mm)

Naxxar: 35.4 mm (492.5 mm)

Dingli: 32.1 mm (393.9 mm)

Mġarr: 34.3 mm (478.2 mm)

Mosta: 45.3 mm (399.9 mm)

Msida: 52.2 mm (478.6 mm)

Sliema: 50.1 mm (464.4 mm)

Valletta: 28.8 mm (306.2 mm)

Imqabba: 26.6 mm (446.9 mm)

Żabbar: 44.0 mm (511.6 mm)

Birżebbuġa: 26.2 mm (356.1 mm)

NATIONAL MEAN: 41.8 mm (461.9 mm)