With a current app tally of 39,860, Windows 8 is set to cross the 40,000 application mark tomorrow, provided a normal Tuesday crop of approvals.

This data, collected by MetroStore Scanner, indicates that since December 27th 5,000 applications have been added to the Windows Store in Windows 8. On a per day basis, Windows 8 is therefore accreting around 156 apps per day. That number is a bit of a misnomer, as all but no apps are approved on Mondays, and Sundays are slow as well.

That rate is down sharply from the 14,557 apps that Windows 8 collected in the 35 days preceding the 35,000 app mark reached in late December. At that point, Windows 8 was collecting applications at a rate of 415 per day.

That the flow of applications was higher through the holiday season was not surprising. Million of Windows 8-based devices were sold during the Christmas cycle, making it a developer opportunity; be in the Store when folks first fire up their machines, and perhaps you’ll catch a viral wave.

However, focusing too heavily on raw figures can be a mistake, as TNW noted before:

The natural caveat to this sort of discussion is that the number of applications for a platform is just that: a statistic. The average quality of the applications contained in the marketplace, and the presence of key apps, can be more important. However, the total tally of applications is akin to the pulse of platform, and the quicker that heartbeat the better.

In December, noting the then current app influx to Windows 8, TNW pointed out that the 50,000 application mark could be reached by the first of February. Given the slowing of app submissions, that date has been pushed back. Employing the last month’s rate, Windows 8 should reach the 50,000 tally on April 3rd.

Windows 8 has completed its launch cycle. As it enters maturity, developer interest will settle. At what mark it will settle at is the question. Microsoft must be slightly irked at how quickly its new Store has slowed.

Image Credit: Kevork Djansezian/Getty Images