Malta is experiencing an increase in “isolated showers” when compared to the less intense “rain”, the Meteorological Office – armed with a century of data – has observed.

The increased occurrence and intensity of short-lived showers, especially in the last quarter of the year, coincides with a decrease of rain, which is defined as more prolonged but less intense.

“The main difference we are seeing is a lack of the continuous light to moderate rain on a larger scale, when compared to the isolated showers,” said forecaster Martina Gatt, who has been at the Met Office for eight years, and Jeffrey Custò, its meteorological systems administrator.

“The latter may generate an equal amount of precipitation but in random areas and in a shorter period, while the former is more ideal for agriculture.” 

Gatt and Custò are among a team of five forecasters, five observers and two administrators who are this month celebrating the Met Office’s 100th anniversary and can draw on extensive archival records, including pages of weather observations documented at specific times of each day in daily observation registers. 

Hand-plotted synoptic charts, forming the basis of weather forecasts prior to the advent of forecasting technologies, also date back to July 10, 1922.

Singling out interesting climatic observations a century down the line, the team also notes that the climate of the Maltese islands has a cycle, especially in terms of precipitation values, with one decade of dry years usually is followed by another of wetness.

The 100-year average stands at 550mm of precipitation, with the current climatic norm (1991-2020) at 543mm. 

A clear example of this cycle was the average precipitation value for the 1940s and the 1950s. Between 1940 and 1949, an average of 480mm of rainfall was measured, followed by a total of 653mm in the following decade.

"Gatt and Custò are among a team of five forecasters, five observers and two administrators who are this month celebrating the Met Office’s 100th anniversary and can draw on extensive archival records, including pages of weather observations documented at specific times of each day in daily observation registers"

Several factors may have had an impact on these climate changes, including the location of the Met Office.

Its moves from Pietà to St John’s Cavalier in Valletta five years later, where it was located underground during the war, and on to Luqa, close to the Flight Information Centre and air traffic control services, by the end of 1946, influenced the type of data gathered.

Along the last 100 years, the type of instruments used, and their accuracy, has also improved drastically, while the level of human error has reduced as information is mainly gathered digitally. 

The introduction of the automatic weather stations in the mid-2000s aided the office by allowing the recording of data from eight areas.

Measuring parameters such as wind direction and speed, temperature, dew point, relative humidity, rainfall, global solar irradiance and atmospheric pressure, the AWSs have also enabled forecasters to monitor weather across the islands in real time, making it easier to issue warnings. 

The heat is on

In the past 100 years, the Met Office has also observed an approximate increase of 1.1 degrees Celsius in the average temperature, as well as a growth in the duration of heatwaves in summer. 

The maximum temperature for this June was 38˚C, while for July, so far, it was 38.8˚C, with one heatwave, as yet, of six days between June 23 and 28. 

In the last decade, heatwaves were not recorded every year, but each time they happened, it was in June.

Only providing a seven-day forecast, upped from five in 2016, it was impossible to say what lay in store in terms of heatwaves for summer, the national weather services provider said.

“Future predications are not possible without proper studies, backed by multiple meteorologists.

“Even then, they would be completely theoretical as multiple volatile factors, in the past and future, played or will play a part in such extrapolation.”

The accuracy of the Met Office’s forecasts stands at around 88 per cent, it said, whose primary role is to provide weather services to the aviation industry, civil and marine. 

But forecast accuracy is expected to be enhanced both for the public and aviation by the introduction of higher-resolution numerical weather prediction models and tephigrams.

The improvements in the pipeline will be effective in particular in the case of fog and low cloud cover, Gatt and Custò announced.

“Certain situations, although quite uncommon, mean adverse weather conditions develop very quickly on our islands and we have to disseminate this new information in a very short time. 

“In these instances, the first priority is to inform the Air Traffic Services, which, in turn, can forward the information to any incoming flights,” they explained. 

Data requests are now more intense, especially following extreme weather events, the forecasters have also observed.

“The interest in weather has always been strong in the Maltese islands. However, lately, we have been noticing a heightened interest in climate change and factors contributing to it. 

“The ‘climate change’ conversation tends to increase during the summer months, prompted by the frequent heatwaves, as well as in spring when less rainfall is recorded than expected,” they noted. 

The Met Office team takes the health, well-being and safety aspect of its job “very seriously and always aims to provide factual rather than sensational information to the public”.

RECORD-SETTING WEATHER EVENTS 

January 16, 1978

Thunderstorm and gale force winds strike the islands, with wind gusts reaching 61 knots and 36.4mm of rainfall measured in less than 24 hours, leaving a trail of damage.

December 2, 1989 

A storm hits the Maltese Islands on December 2, 1989, during the Malta Summit between George H.W. Bush and Mikhail Gorbachev. In total, 68.1mm of rainfall were recorded, while the mean wind speed was that of 21.4 knots and a highest gust reaching 49 knots. 

October 24, 2010

102.2mm of rainfall are measured in Luqa within a 24-hour period, with certain areas across Malta suffering flooding and extensive damage. Flooding in Qormi leads to a particularly memorable incident where coffins from an undertaker’s warehouse are carried out into the streets on the floodwater.

February 9, 2018

Prolonged precipitation yields 117mm of rainfall, making the ninth day of the month the second wettest since 1923. The precipitation climate norm for the whole month of February is 56.9mm (1981-2010).

October 2018

Stormiest month since 1922, with 16 thundery days. The month also yields 189mm of precipitation, which is well over the monthly climate norm of 75.6mm (1981-2010).

February 23 -24, 2019 

A severe Gregale storm batters the Maltese Islands, with gusty winds reaching 54 knots. A total of 43.8mm falls on February 23, amounting to almost half the amount of rain received throughout February. Registering a total of 93mm of rainfall spread out over 11 days, February is wetter than the climate norm, but produces just half the amount of rain recorded in February 2018.

January 9, 2021

The maximum temperature peaks at 25.8˚C, setting a new monthly record, as a south-westerly wind blows from the Sahara Desert, fanning the air temperature. Warm air is trapped overnight due to the presence of a dense and multi-layered cloud cover.

June 2021

A long heatwave starts on June 20 and lingers on until July 1. On the last day of June, the temperature shoots up to 41.5˚C, setting a new temperature record for the month.