Bulletin 13 - March 1981: Climatological Summary for 1980

Climatological Summary for 1980

1980 was a dry year with wet bulb maximum and dry bulb means above the normal and many hazy or dusty days.

Although the yearly mean monthly dry bulb temperature was about 1.0°C above the normal (27.72°C against the norm of 26.79°C), the daily absolute maximum was only exceeded in October when a temperature of 41.2°C was recorded. This compares with an October mean 1971-1979 of 39.2°C. During the first four months of the year and also in July, September, October and December, the normal daily maximum was exceeded. Absolute minimum temperatures were higher than normal throughout the year except in February, March and December. August remained constant at 26.4°C. Generally speaking, absolute daily minimums over the past decade are more frequent between 1971 and 1975.

New absolute maximum wet bulb temperature extremes were recorded during February, April, July and October whilst generally this element was about 0.8°C above normal (27.4°C for 1980 against 26.59°C normal).

The yearly rainfall total was only 18.88 mm, compared to a norm of 43.9 mm, the most noticeable decrease being in January when a total monthly fall of 2.6 mm was measured. The January norm for 1971-1979 is 12.4 mm with an extreme of 35.2mm in January 1977. All months, however, were well below average. Other extremes 1971-1979 include recordings of 55.1 mm for February 1976 (9.0 mm February 1980), 55.3 mm for March 1972 (5.4 mm March 1980) and 29.7 mm for August 1975 (nil August 1980).

Throughout the year, 69% of the days had visibility during the day reduced to less than 8000 meters due to lifted sand, dust, haze, smoke etc. and a total of 23 days with fog were reported compared to the yearly normal of 20.9. During the summer months, May to September inclusive, a total of 128 days out of a possible 153 were recorded with reduced visibility.

From a yearly total of eight sandstorms, five occurred in March. During one sandstorm, on 19th March, a maximum wind speed of 44kt gusting to 47kt was measured whilst visibility fell to 500 meters. A sandstorm on 11th February was followed later in the day by thunderstorms.

The daily average number of sunshine hours was exceeded in January (8.3 against a 1971-1979 norm of 7.5), March (8.5 against 7.9), April (10.5 against 9.3), July 10.7 against 10.2), and August (10.4 against 9.8). A 10-year extreme of 10.4 hours was recorded for January 1980.