12 June 1963
The Coldest day in Pretoria in recent history was on 12 June 1963. The temperatures plummeted to a minimum of -3, 6 and a maximum of 7, 5 degrees Centigrade. It had been a 110 years since temperatures were that low and it has never been as cold since. In winter the daily average maximum temperatures in Pretoria is 20 degrees with a minimum of 1 degree centigrade.
References

My Weather 2, 'Country Overview For South Africa', from myweather, [online], Available at: www.myweather2.com [Accessed 3 June 2013]|Climate Charts, 'Pretoria, South Africa', [online], from climate-charts, [online], Available at: www.climate-charts.com [Accessed on 3 June 2013]