Leaks:

Hardware

Switch - 670.000
PS4 - 160.000
XBO - 91.000

Software

Physical only (No digital)

Mario 3D All star - 1.165.000
Marvel's Avengers - 450.000
Animal Crossing: New Horizon - 180.000

official Results:

State of the market

Consumer spending across video game hardware, content and accessories reached $4.3 billion in September 2020, 10% higher than a year ago. Mobile, hardware and accessories were among the largest growth segments.

Year-to-date spending totaled $33.7 billion, 21 percent higher than the same period in 2019.

Content

Marvel's Avengers was the best-selling title of September. Launch month dollar sales of Marvel's Avengers were the 2nd highest for any superhero game in US history, trailing only Marvel's Spider-Man. Marvel's Avengers debuted as the #7 best-selling game of 2020 YTD.

Super Mario 3D All-Stars was the 2nd best-selling game of September, and the #10 best-selling game of 2020 YTD. Super Mario 3D All-Stars generated the 2nd highest launch month physical dollar sales of any 2020 release, trailing only Animal Crossing: New Horizons.
Super Mario 3D All-Stars launch month physical dollar sales rank as the 6th biggest for a Nintendo published title in U.S. history.

Tony Hawk's Pro Skater 1 + 2 was the 4th best-selling game in September. The release achieved the highest launch month dollar sales of any title in Tony Hawk franchise history, surpassing Tony Hawk's Underground 2 which originally launched in October 2004.

Crusader Kings III was the 7th best-selling game of September. With just one month of sales, Crusader Kings III ranks as the best-selling release in franchise history. The title also experienced the highest launch month dollar sales of any title published by Paradox Interactive.

Software charts

Hardware

September 2020 video game hardware spending increased 15% vs YA, at $277 million. Growth in sales of Nintendo Switch offset declines on other console platforms. Nintendo Switch was the best-selling console during September in both dollars and units.

Year-to-date spending on hardware has increased 22 percent when compared to a year ago, to $2.3 billion.

Accessories

Spending on Accessories reached a September record $191 million, gaining 30 percent when compared to a year ago. Year-to-date spending has increased 26 percent, to an all-time high $1.6 billion.

Gamepad and Headset/Headphone spending each set new September and year-to-date U.S. sales records.

The Xbox Elite Series 2 Wireless Controller was the best-selling accessory of both September and year-to-date (dollar sales).

Thanks to Mat Piscatella for the break down !

Archivie

2020: January, February, March, April, May, June, July, August,
2019: January, February, March, April, May, June, July, August, September, October, November, December
2018: January, February, March, April, May, June, July, August, September, October, November, December
2017: January, February, March, April, May, June, July, August, September, October, November, December
2016: January, February, March, April, May, June, July, August, September, October, November, December
2015: January, February, March, April, May, June, July, August, September, October, November, December
2014: January, February, March, April, May, June, July, August, September, October, November, December
2013: January, February, March, April, May, June, July, August, September, October, November, December
2012: January, February, March, April, May, June, July, August, September, October, November, December
2011: January, February, March, April, May, June, July, August, September, October, November, December
2010: January, February, March, April, May, June, July, August, September, October, November, December
2009: January, February, March, April, May, June, July, August, September, October, November, December
2008: January, February, March, April, May, June, July, August, September, October, November, December
2007: January, February, March, April, May, June, July, August, September, October, November, December

[NSW] 650K
[PS4] 200K
[XBO] 60K

[NSW] 550K
[PS4] 160K
[XBO] 60K

[NSW] 750K
[PS4] 135K
[XB1] 45K

VGC tracking for NSW is at 749K I believe.

NPD August weekly average was 126K, and I would wager that the weekly performance was backloaded (weaker stock in July that bled into early August and then dialed up throughout the month). Considering that + launch of Mario 3D All Stars, I'd expect Sep weekly average to be 150-160K, so 750-800K range.

NSW] 766K
[PS4] 153K
[XBO] 72K

Is there an exact date when the September NPD will be released?

Switch 801k
Ps4 199k
Xo 50k

Is September considered a 5-week month or a 4-week month?

5 weeks.  All quarter ends are 5 weeks.

Jan 4

Feb 4

Mar 5

Apr 4

May 4

Jun 5

Jul 4

Aug 4

Sep 5

Oct 4

Nov 4

Dec 5

That comes out to a clean 13 weeks per quarter, and 52 weeks per year (364 days).

Every 7 years or so, there will be an extra week tacked onto Dec or Jan in order to make sure the calendar doesn't fall too far out of alignment (364 days vs 365/366 days).