Middelburg shows warm summers and cold winters representative of the Highveld climate.
Rainfall commonly occurs as thunderstorms. It experiences an annual average rainfall of 740 mm (Figure 3.1) and vary from average 132 mm in January to 9 mm during the winter season. It experiences severe frosts during winter season, however, during the summer season it experiences hail storms. Rainfall mostly occurs between November and February. Water is lost in the system due to mean annual potential evaporation of 2 060 mm (Steve Tshwete LM SDF., 2008).
Figure 3.1. Annual mean rainfall of Middelburg (Steve Tshwete LM SDF., 2008).
The temperature of Middelburg is also representative of the temperatures occurring on the Highveld with the lowest temperature being 3 0C in July and a maximum of 31 0C in January. The average annual winter temperature is found to be 15 0C whereas average summer temperature as 27 0C (as shown in Figure 3.2) (Steve Tshwete LM SDF., 2008).
Figure 3.2. Annual maximum, mean and minimum annual temperature of Middelburg (Steve Tshwete LM SDF., 2008).
The approximately 1800 Ma Wilgerivier Formation of the Waterberg Group with a maximum thickness of 2000 m unconformably overlie the Pretoria Group, Silverton Formation and Loskop Formation (Callaghan et al. 1991).
The Wilgerivier Formation comprises clastic sedimentary rocks, which include sandstone and conglomerate. The rocks consist of red to red-brown sandstone and quartzite, with grit bands that dip towards the north at angles of 10º to 15º. It is intruded by a number of diabase sills and dykes of several metres (Steve Tshwete LM SDF., 2008).
3.1.4 Topography and drainage
Middelburg comprises undulating topography in the southern part at an approximate height of 1600 m above sea level. Numerous hills and steep inclines are located towards the northwestern part of the Middelburg at a height of 1400 m. Drainage is found towards the north to north western portion of the southern part of the area, and south to southwest portion in the northern part of the area, towards the Klein Olifants River (Steve Tshwete LM SDF., 2008).