Is it problematic to daven outdoors?
One should not daven in an open area outdoors, and should daven in a closed building, or a sheltered area.
The Gemara (Berachos 34b) writes that it is wrong (arrogant — chatzuf) to daven in an open field.
Rashi explains that in an open field, one doesn’t feel fear of the King, and one doesn’t pray with a broken heart. Tosafos, however, understands that the concern is for passers-by, who are liable to disturb a person’s davening.
The Magen Avraham (90:6) rules that the problem is that davening outside makes a haugty statement: “Even though there are passers-by, they will not disturb my intent in davening!” This is arrogant and wrong.
The Shulchan Aruch (90:5) rules that one should not daven in an open place, and the Mishnah Berurah (11) adds that those who are always travelling should can daven in an open place, but should try to daven by a tree.
Therefore, although it is not forbidden to daven outdoors, it is wrong to daven in an open area, and one should seek a sheltered place.