It will be the first time a pontiff has visited Latvia since 1993 when Pope John Paul II came.
According to the Chancery of the President, an official announcement is due soon from the Vatican confirming the exact schedule of the Pope's visit.
Rumours of the imminent announcement first came out a few days ago in Estonia following the visit of a papal representative.
"According to the information available to us, a visit can take place from September 16 to September 18," said Tõni Linnamäe, the Estonian President's press secretary.
The Latvian Foreign Ministry said that the Pope was invited to visit Latvia in 2018, and according to tradition, official confirmation of such visits is given after the parties have agreed upon it.
A Christian can never be a pessimist!— Pope Francis (@Pontifex) November 13, 2017
The visit to the Baltics should provide contrasting experiences for the Pope. Lithuania is staunchly Catholic, Latvia has Lutheran, Catholic, Orthodox and pagan religious traditions and Estonia is by some measures the least religious country in the world.
It is now 800 years since crusading knights answered a call by Francis' predecessors Pope Celestine III and Pope Innocent III to invade the pagan regions of the Baltic littoral and forcibly convert the local populations to the cross.
Latvian President Raimonds Vējonis has in the past described himself as "pagan" by religious persuasion, so it will be interesting to see if the crusades form a topic of conversation between the pair.
Argentine Pope Francis is officially the 266th bishop of Rome and sovereign of the Vatican. He was preceded by Pope Benedict XVI who retired from the post voluntarily.