2015 was indeed a very dry year in South Africa
The South African Weather Service has compiled a dataset of monthly average rainfall per province for all 9 provinces dating back to 1904. This dataset was used to calculate the annual total rainfall (Jan – Dec) for South Africa over the 112-year period from 1904 to 2015. The data was analysed and revealed very interesting information.
The annual average rainfall for South Africa, calculated over the full 112 years, is 608 mm.
Over the full 112-year period, the lowest annual total rainfall for South Africa was indeed for the period Jan – Dec 2015 with an annual total of only 403 mm. Following in the table below are the 13 years when the annual total rainfall for South Africa was less than 500 mm.
|
YEAR |
Annual Total Rain (mm) |
|
2015 |
403 |
|
1945 |
437 |
|
1992 |
440 |
|
2003 |
446 |
|
1935 |
451 |
|
1919 |
451 |
|
1965 |
452 |
|
1926 |
468 |
|
1916 |
476 |
|
1927 |
488 |
|
1912 |
493 |
|
1982 |
496 |
|
1941 |
496 |
The longest period of consecutive years where the annual total rainfall was below the period average of 608 mm per annum, was the 6 years starting in 1944. If an annual average is calculated for this 6-year period, it is 544 mm.
|
YEAR |
Annual Total Rain (mm) |
|
1944 |
582 |
|
1945 |
437 |
|
1946 |
569 |
|
1947 |
573 |
|
1948 |
548 |
|
1949 |
555 |
|
Average for 6 years |
544 |
The next longest period where the annual total rainfall was below the period average of 608 mm per annum, were 2 periods of 4 consecutive years each.
The first period started in 1930 and the second period started in 2012.
|
YEAR |
Annual Total Rain (mm) |
|
1930 |
514 |
|
1931 |
548 |
|
1932 |
510 |
|
1933 |
505 |
|
Average for 4 years |
519 |
***
|
YEAR |
Annual Total Rain (mm) |
|
2012 |
601 |
|
2013 |
591 |
|
2014 |
581 |
|
2015 |
403 |
|
Average for 4 years |
544 |
The annual average rainfall per annum for the 4 years 1930 – 1933 is 519 mm. The annual average rainfall per annum for the 4 years 2012 – 2015 is 544 mm.
Although the annual total rainfall for South Africa for the 12 months Jan – Dec 2015, was the lowest annual total since 1904, the 4-year period 1930 – 1933 might still be the driest continuous period experienced in South Africa.
Statement issued by Elsa de Jager, Unit Manager: Climate Information, South African Weather Service, 13 January 2016
