May 2013 beset by ‘sand storms’

May 2013 was a typical May but windy and very dry. In fact, the monthly total of 0.9mm was far below the average of 8.5mm. There were 4 days of light rain, two of which were with lightning or thunder and one with hail. There were various completely dry Mays over the years, including that of last year. The wettest May ever was in 1992 with 34.3mm.

The mean monthly temperature of 20.4°C was exactly equal to the average expected for the month. However, days were colder than average with the mean monthly maximum temperature of 23.4°C being 0.7°C below average, while the nights were warmer than average with the mean monthly minimum temperature of 17.4°C being 0.8°C above average.

This seemingly bizarre situation was brought about by the moderate to strong winds that lowered daytime temperatures, but did not allow night time ones to go down too low.

The coolest May ever was in 1991 with 17.8°C while the hottest ever was in 1988 and 1999 with a mean monthly temperature of 21.6°C.

The hottest day in May 2013 was on the 2nd with a high of 29.3°C. The coldest night in May 2013 was on the 27th with a low of 14.9°C. The hottest May temperature ever recorded was 37.4°C on 23rd May 2006 while the coldest was 10.5°C on 2nd May 1992.

The wind blew mainly from the west-northwest with an average wind speed at Zebbug Malta of 11.4km/h. The strongest gust at Zebbug Malta was of 70.3km/h on the 22nd from a west-southwesterly direction during the northwards passage of a north African low pressure system. A much higher gust of 103.6km/h was measured at Mellieha on the 16^th as another north African low moved northwards towards Italy.

The mean monthly sea-level pressure was 1013.3hPa, with the highest of 1020.5hPa on the 7th and the lowest of 997.6hPa on the 16th.

There were also two ‘sand storms’, one on the 18th with a minimum visibility of around 3km and another on the 22nd that brought the visibility down to around 1km.