Northern Ireland are up to 20th place in the Fifa rankings - their highest ever position.
Michael O'Neill's men are in contention for a World Cup play-off place and their ranking in October will determine if they are one of the seeded teams.
Northern Ireland have enjoyed a successful run under O'Neill, climbing from 129th place in the Fifa rankings for September 2012.
Their previous best position was 22nd in July 2017.
The Republic of Ireland, also hoping to be one of eight teams in the European play-offs for Russia 2018, are down five places in the latest Fifa rankings to 34.
|Rankings of teams currently in play-off positions (top four to be seeded)|
Northern Ireland's recent qualifying wins over San Marino and the Czech Republic mean they are guaranteed a top two finish in Group C.
World champions Germany have maximum points with two matches to play and a draw against O'Neill's men in Belfast on 5 October would ensure they finish top.
Northern Ireland, who would then be runners-up and likely to be in the play-offs, finish the campaign away to Norway three days later.
That result could have a bearing on whether the boys in green are ranked high enough to be one of the four seeded countries.
The draw for the play-offs takes place on 17 October, based on the Fifa world rankings updated a day earlier.
When the draw for the play-offs is made, the eight teams will be separated in two pots with the four highest-ranked teams seeded in one pot.
Being seeded would mean Northern Ireland avoiding teams such as Portugal and Italy.