Two weeks ago I made a post about likely temple sites for future temples. These sites were determined by a quantitative method I developed which factors in the number of stakes and districts in the area, distance from the closest existing temple, stakes created before 1981, and Saturday endowment schedule.
I feel that a fifth element also contributes to the likelihood of a new temple. Out of the 76 temples outside of the United States, only six exist in cities which do not have a mission based in them. The presence of a mission of the Church in a city increases the likelihood a temple being announced in that city. I am not sure how I am going to factor this fifth variable in yet quantitatively, but I feel that it would improve the accuracy of the model developed.