He was cared for by his father's older brother, Peter Tempelman, who served as priest in the Östra Stenby congregation.

His uncle was a man of scientific interest, who collected books and had contact with the Royal Swedish Academy of Sciences.

His received his early education at home and continued studying, along with his cousin, at the high school in Linköping.

At Uppsala University in 1763, he began studying theology and the humanities while working as a tutor for income.

But he eventually immersed himself in science, following in the likes of Carl Linnaeus, Anders Celsius, and Samuel Klingenstierna.

In October 1776, Gustav III assigned Tempelman to be an information aide for fortifications; he trained under Fredrik Dederichs who taught prospective officers and architects since the 1750s, including Erik Palmstedt.

He visited Naples with Carl August Ehrensvärd and they also made a trip to Pompeii and Vesuvius, returning home via Venice, Milan, Genoa, Antibes, Marseille, and Paris.

The office of the Superintendent of Antiquities, however, was still busy designing churches, schools, and hospitals, especially outside Stockholm, and this is where Tempelman gave significant effort.