Analysts are predicting the the launch of the iPhone 5S and 5C will set new records for Apple with the company selling up to 13M handsets in the first nine days following the predicted availability date of 20th September. That’s close to double the 7M phones sold in the first nine days of the iPhone 5 launch.

The prediction is made by Pacific Crest analyst Andy Hargreaves, cited by AllThingsD:

For Hargreaves, that means fourth-quarter iPhone sales of 31 million iPhones. Of those, he figures 10 million will be the new models. That’s a big number considering the limited number of selling days left in the quarter, but Hargreaves feels it could go higher still — to 13 million, with some “extremely efficient supply chain management” … 

Hargreaves has also forecast that deals with China Mobile and Japan’s NTT DoCoMo would boost annual sales by 15M. ISI analyst Brian Marshall considers that way too conservative, predicting an extra 38.7M sales in calendar year 2014.

The huge disparity between the two numbers serves to underline the first law of analyst predictions: no one really knows. While some kind of China Mobile deal is as close as it can be to a done deal, we don’t yet know the terms of that deal, and – critically – we don’t know the retail price of the 5C. A $100 difference in retail price is likely to be reflected in millions of sales.

We don’t know whether China Mobile will offer the iPhone on subsidised contracts – unlike the U.S. market, most handsets are sold outright. Contracts could make a massive difference to sales.

We don’t know the marketing spend going to be thrown at the iPhone in China by either China Mobile or Apple.  We don’t know how local manufacturers, known to be fast followers, will respond. I could go on. The bottom line is that there are way too many variables in the mix to place too much reliance on specific forecasts.

But record sales? Yep, that one looks like a no-brainer. And efficient supply chain management? That’s how Tim Cook got to be where he is today. This month is going to be an interesting one.