How far below the earths surface do you need to drill on average to get a temperature of 90 C?

Question

the area I'm concerned with is alberta approc 1000 M above sea level

Answer 1

it should be in lithosphere.but the deep point will depend on location.in japan it will come at less deep point while in antarctic u will have to go a long down.

Answer 2

A long ways.  That area is not significantly geothermally active regionally, so you'd have to go several thousand feet to get that hot.

Answer 3

Normal geothermal gradient is about 30 degrees C per kilometer, but varies with location.  Higher gradients occur where magma upwelling at depth is occuring, and lower gradients can be observed where significant groundwater flow transfers (convects) heat out.

Ballpark guess for your case would be three kilometers.