The CTCT has previously not been completed because of heat, wind, fire, Covid-19 and now you want it moved because it happened to rain on a similar day to when the race might have been had it not already been cancelled? It might be easier to just not hold it at all if you want to look for reasons that a date isn't suitable. March is probably the best chance you have of avoiding heat, wind, rain etc in Cape Town but the organisers have no control beyond hope and luck. Just out of interest - what alternative date would you like? Let's see if we can find a good reason why you're wrong.