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Public Document I WCS-CLS-CI-ACS-2018

Annual Climate Summary 2018

© EUMETSAT

Annual Climate Summary for South Africa

2018

Public Document ii WCS-CLS-CI-ACS-2018


South African Weather Service Private Bag X097 Pretoria 0001 © South African Weather Service Disclaimer: While every reasonable effort has been made to relate objective and realistic information, the South African Weather Service does not assume any legal liability or responsibility for the accurateness, completeness or usefulness of any information in this publication. Please cite as follows: South African Weather Service. 2019. Annual Climate Summary for South Africa 2018. Pretoria. South Africa. Cover: The picture is indicating a sinkhole in Valhalla, Centurion, Gauteng that swallowed a car on 23 March 2018. Luckily the driver, who indicated that it was still dark and he could not see the sinkhole, escaped unharmed. The sinkhole developed following flash floods in the area. Image source: https://rekordcenturion.co.za/141414/newsflash-car-swallowed-centurion-sinkhole/

Public Document iii WCS-CLS-CI-ACS-2018


Preface

This publication gives an overview of the climate of South Africa on an annual basis. Topics covered include: The most noteworthy severe weather events for 2018. A climate overview for 2018 where temperature and rainfall are compared with previous years. Tables of tem-

perature and rainfall figures and anomalies for selected climate stations are also provided. Indications of drought using the Standardized Precipitation Index (SPI). Monthly overview, which includes a chronological summary of temperature and rainfall anomalies throughout

the year, maps of maximum and minimum temperature deviations from the 1981-2010 normal, the Standardized Precipitation Index and lightning-stroke densities.

The input data used have been obtained from the climate data archive of the South African Weather Service. The contents of the publication was produced by Mr Musa Mkhwanazi, Mr Joe Matsapola, Mr Lucky Dlamini, Miss Elsa de Jager, Mr Sifiso Mbatha and Dr Andries Kruger of the Climate Services Department, South African Weather Service. The intended audience for this publication is the general public, commerce and industry, as well as tourism.

Public Document iv WCS-CLS-CI-ACS-2018


Table of Contents

Page Preface iii Table of Contents iv Severe weather events 1 Climate overview 2 Temperature 3 Rainfall 5 Distribution of climate stations used in rainfall and temperature tables 11 Indications of drought 12 Monthly maps 13

Public Document 1 WCS-CLS-CI-ACS-2018


Severe weather events — 2018



Climate overview Temperature Mean annual temperature anomalies were calculated from 26 spatially well-distributed and representative climate stations. The mean annual temperature for 2018 for South Africa was in general 0,52 °C above the 1981-2010 clima-tological normal. Based on the 1981-2010 climatological normal, 2018 is ranked the 4th warmest year for the 68 years from 1951 to 2018.



Maximum Temperature (°C) overview for some long-term climate stations for 2018

Station Average Normal Rank (Highest

since 1981)

Highest Annual Average

Lowest Annual Average

Highest Daily Highest Daily Lowest Daily Lowest Daily

2018 (1981-2010) (since 1981) (since 1981) 2018 (since 1981) 2018 (since 1981)

Limpopo Province

Thohoyandou 28.2 27.5 6 29.2 (1992) 26.0 (2000) 40.1 42.6 (1992-02-26) 14.6 9.0 (2017-12-07)

Polokwane 26.3 25.2 3 26.9 (1992) 23.9 (1981) 35.7 38.4 (1992-02-26) 14.7 8.4 (2016-06-13)

Gauteng

Pretoria Unisa 25.4 25.8 16 28.9 (2015) 22.3 (1999) 38.7 42.7 (2016-01-07) 10.6 6.0 (2012-08-07)

Johannesburg 23.2 22.3 4 23.7 (1992) 24.3 (2015) 34.0 35.6 (2016-01-07) 12.1 4.0 (2012-08-07)

North-West

Mafikeng 28.3 26.5 2 29.0 (2015) 25.3 (2009) 40.7 41.5 (2016-01-07) 16.4 8.9 (2006-08-02)

Vryburg 27.1 27.1 25 30.4 (2015) 25.5 (2006) 38.4 43.7 (2016-01-06) 19.3 7.4 (1996-07-07)

Mpumalanga

Lydenburg 24.8 23.2 3 25.6 (2015) 22.1 (2000) 34.4 34.6 (1992-02-26) 10.8 5.8 (1996-07-17)

Skukuza 32.6 30.0 1 32.6 (2018) 28.4 (1981) 46.3 48.3 (2012-02-10) 11.0 11.0 (2018-08-09)

Free State

Frankfort 26.1 24.1 3 26.8 (2015) 22.7 (2000) 37.1 40.4 (2016-01-07) 10.7 3.5 (1981-09-10)

Bloemfontein 25.7 24.9 8 27.2 (2015) 23.2 (1981) 38.0 42.0 (2016-01-06) 12.5 5.1 (2012-08-07)

KwaZulu-Natal

Ladysmith 26.2 25.4 8 27.9 (2015) 23.4 (2001) 39.9 42.9 (2016-01-06) 7.1 2.9 (2001-09-13)

Durban 25.7 25.4 7 26.3 (2010) 24.6 (1997) 34.4 40.4 (2010-9-14) 14.8 12.6 (2008-09-20)

Northern Cape

Upington 29.9 29.2 7 30.8 (2016) 27.8 (1991) 42.6 44.1 (1992-01-27) 10.5 7.5 (1981-08-28)

Calvinia 25.1 24.6 8 25.9 (2017) 23.1 (1996) 39.3 41.9 (1993-01-03) 5.4 4.0 (2000-07-15)

Western Cape

Cape Town 23.1 22.7 4 23.4 (1999) 21.4 (1992) 36.4 42.3 (2015-03-03) 12.3 9.6 (2000-07-15)

George 22.2 21.7 4 22.6 (1999) 20.6 (1981) 40.3 42.9 (2002-12-07) 11.4 8.3 (2012-07-13)

Eastern Cape

Port Elizabeth 23.1 22.6 6 23.3 (2016) 21.8 (1995) 37.6 40.1 (2006-04-06) 13.5 9.3 (2002-08-04)

East London 23.6 23.3 10 27.1 (2012) 21.6 (2013) 34.6 42.9 (1997-10-04) 14.6 9.2 (2013-07-23)



Minimum Temperature (°C) overview for some long-term climate stations for 2018

Station Average Normal Rank (Highest

since 1981)

Highest Annual Average

Lowest Annual Average

Highest Daily Highest Daily Lowest Daily Lowest Daily

2018 (1981-2010) (since 1981) (since 1981) 2018 (since 1981) 2018 (since 1981)

Limpopo Province

Thohoyandou 15.7 15,3 10 16.8 (1992) 13.5 (2010) 24.2 26.6 (1992-02-27) 6.4 1.8 (1985-07-13)

Polokwane 12.8 11,7 1 12.8 (2018) 9.5 (2013) 22.1 23,4 (2003-12-09) 2.7 -2.5 (1981-06-17)

Gauteng

Pretoria Unisa 10.8 11.5 23 12.9 (2015) 7.6 (1999) 19.7 24.8 (2019-11-10) 0.6 -3.0 (2003-8-21)

Johannesburg 11.1 10,1 7 11.5 (1983) 8,6 (1994) 21.6 23.0 (2007-01-27) -2.7 -7.0 (2003-08-21)

North-West

Mafikeng 11.6 11,5 26 13.6 (2016) 10.6 (1984) 23 25.0 (2013-01-26) -1.7 -6,1 (1994-06-29)

Vryburg 6.7 9,5 38 10,5 (1983) 6.7 (2018) 23.2 24.5 (1984-02-14) -8.2 -9.0 (2014-07-09)

Mpumalanga

Lydenburg 9.6 9,5 28 13.9 (2015) 8.6 (1985) 18.3 20.4 (1997-02-22) -0.7 -4.2 (1994-06-30)

Skukuza 15.1 14,3 7 15.8 (2010) 12.4 (2014) 24.9 30.2 (2010-10-12) -2.3 -3.1 (2012-06-13)

Free State

Frankfort 7.7 6,8 12 8.4 (2003) 5.2 (1994) 18.1 20.6 (1992-12-4) -8.7 -11.7 (2014-06-12)

Bloemfontein 7.3 7,5 22 9.2 (2016) 5.8 (2007) 20.7 23.4 (2015-12-01) -8 -11.7 (1992-06-26)

KwaZulu-Natal

Ladysmith 9.4 10,7 37 13.6 (1988) 8.6 (2017) 21.9 23.8 (1990-11-14) -4.2 -5.8 (2011-07-11)

Durban 17.3 16,5 7 17.5 (1985) 16.1 (2013) 24.1 26,1 (1983-02-11) 5.5 2.6 (1967-08-18)

Northern Cape

Upington 12.2 12,5 27 14.2 (1999) 10.9 (2011) 24.7 29.6 (1985-01-03) -5.7 -5.9 (2018-07-04)

Calvinia 9.3 8,4 2 9.7 (1999) 7.4 (1986) 22.4 28.0 (1990-02-7) -4.7 -6.6 (2003-07-19)

Western Cape

Cape Town 12.2 11,4 9 12.6 (2014) 10.9 (1982) 21.5 22.4 (1992-02-20) 1.9 -0.4 (1988-06-17)

George 11.8 11,2 14 12.6 (1999) 11.0 (2017) 22.5 25.1 (1985-10-11) 2.5 1.0 (1986-07-03)

Eastern Cape

Port Elizabeth 12.5 13,5 33 14.3 (1985) 12.2 (2002) 22 23.4 (1999-01-29) 1.1 0.0 (1992-06-27)

East London 14.2 14,4 30 18.9 (2012) 14.1 (1990) 21.6 26,5 (1991-04-20) 4.8 1.2 (2013-06-13)



Rainfall

In general South Africa received near-normal to below-normal rainfall during 2018. However, along the west coast of the Western Cape, as well as over the north-western parts of KwaZulu-Natal more than 125% of normal rainfall (reference period 1981—2010) was received.



Rainfall (mm) overview for some long-term climate stations for 2018

Station Total 2018

Normal (1981-2010)

Highest Annual Total

(since 1981)

Lowest Annual Total

(since 1981)

Highest Daily Total

2018

Highest Daily Total

(since 1981)

Number of days with rain >= 1mm

(2018)

Average number of days per year with

rain >= 1mm (1981-2010)

Limpopo Province

Thohoyandou 609 765 1654 (2000) 331 (1983) 68 156 (2000-01-16) 47 58

Polokwane 407 491 950 (1996) 256 (2002) 110 110 (2018-02-19) 34 45

Gauteng

Pretoria (Burgers Park) 542 685 1191 (2006) 362 (1992) 120 163 (2000-10-22) 35 47

Johannesburg 520 750 1089 (2000) 443 (1984) 77 110 (1985-10-30) 57 71

North-West

Mafikeng 428 544 874 (1997) 293 (2015) 63 128 (1995-11-18) 45 52

Vryburg (Welgeleven) 348 421 810 (1988) 123 (2015) 58 121 (1988-02-20) 22 34

Mpumalanga

Nelspruit 626 662 1233 (2000) 301 (2003) 65 106 (2000-02-06) 56 73

Skukuza 223 590 1116 (2000) 151 (2015) 27 140 (2012-01-18) 29 49

Free State

Frankfort 748 669 1039 (1996) 351 (1999) 61 122 (1995-12-16) 66 71

Bloemfontein 426 569 1064 (1988) 260 (1992) 53 142 (1988-02-21) 53 58

KwaZulu-Natal

Ladysmith 597 749 1111 (1987) 300 (1993) 44 141 (1987-09-29) 70 68

Durban 866 1021 1422 (1996) 471 (1992) 52 265 (1996-01-12) 79 87

Northern Cape

Upington 109 189 364 (1991) 53 (1986) 20 85 (1996-02-29) 17 24

Calvinia 143 209 379 (1995) 95 (2003) 26 59 (2010-10-15) 24 34

Western Cape

Cape Town 422 542 707 (1996) 323 (2010) 34 94 (1993-04-11) 66 68

George 514 716 1220 (1981) 374(2009) 59 230(2006-08-01) 76 80

Eastern Cape

Port Elizabeth 416 581 1033 (2012) 401 (2008) 41 224 (1981-03-25) 59 71

East London 570 855 1318 (1985) 550 (1981) 49 313 (2002-08-15) 74 79



Distribution of climate stations used in rainfall and temperature tables



Indications of drought

24-month SPI for January 2017 to December 2018 12-month SPI for January 2018 to December 2018

A meteorological drought is defined on the basis of the degree of dryness in comparison to “normal” or average amounts of rainfall for a particular area or place and the duration of the dry period. This is what is termed a meteoro-logical drought. The Standardized Precipitation Index (SPI) is an index based on the probability of rainfall for any time scale and can

assist in assessing the severity of drought. Drought usually occurs when moisture supply is abnormally below aver-

age for periods of up to two years, where after desiccation occurs. A 12-month and 24-month SPI is a comparison of

the precipitation for 12 and 24 consecutive months with the same 12 and 24 consecutive months during all the previ-

ous years of available data respectively. SPI’s of these longer timescales are useful in identifying areas of drought,

as they are linked to streamflow, reservoir levels and even groundwater levels. The most noteworthy in the 24-month

SPI map below are the moderately dry to extremely dry western parts of the Northern Cape, extending to the West-

ern Cape.



Following are monthly maps for Maximum temperature deviations from the 1981-2010 normal Minimum temperature deviations from the 1981-2010 normal Standardized Precipitation Index (SPI), indicating dry areas Lightning-stroke density indicating the number of strokes per square kilometer

Monthly maps



January 2018

Maximum temperature deviations

SPI Lightning-stroke density

Minimum temperature deviations



February 2018 Maximum temperature deviations





March 2018






April 2018






May 2018






June 2018






July 2018






August 2018






September 2018






October 2018






November 2018






December 2018




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