The Mandela Marathon is held at end of August each year; typical temperatures are lows of 8-10C and highs of around 22-25C.
The race starts in Edendale just outside Pietermaritzburg which is accessible by light aircraft SAA flights from Johannesburg. It lies about 120km from Durban Airport.
You can also subscribe to the AIMS calendar in your calendaring application of choice, whether on your phone, tablet or computer. Simply subscribe to webcal://aims-worldrunning.org/events.ics in your calendar app.