Method
Daily Maximum Temperature in January
Physiological and growth processes reach their optimum in the region of 28-30°C air temperature and decline rapidly above 35°C. At 40-45°C these processes come to a halt and damage (e.g. bleaching, sunburn) can occur in exposed tissues.
The mean monthly day-time maximum temperature (Tmax) in mid-summer (January) was calculated from daily temperature data. More detail is provided in the section Background: Climate Change Modelling.
The modelling for the intermediate future (2050s) was conducted using five different CMIP3 GCMs (Schulze, 2011).
Maps
Map Information
The Breede Valley has a historical Tmax (January) of 28-30°C (Slanghoek, Nuy, Bonnievale, McGregor) and 30-32°C (Worcester, river downstream of Brandvlei Dam, Robertson, Ashton). Climate model projections for the intermediate future (mid-century) show an increase of up to 2.1°C (eastern areas), slightly higher in Robertson, Worcester and the central reaches of the Breede River, and up to 2.25°C in the Slanghoek area upstream of Worcester.