"Place the pot somewhere where it is 20–22 degrees warm."

Place the pot somewhere where it is 20–22 degrees warm.

The double where sounds a bit silly. Is there a better way to word this sentence? "Someplace 20-22 degrees warm" sounds too informal.

Solution 1:

Place the pot where the cat can't reach it.

This would be the simplest, default construction. It will do in many cases. The point is that somewhere as the antecedent of where is superfluous, because, if you use where without an antecedent, something like somewhere is already implicit in it.

Solution 2:

Place the pot somewhere that is 20-22 degrees warm.

Solution 3:

The smallest change would be to replace "somewhere" with "someplace".

Place the pot someplace where it is 20-22 degrees warm.

_{Note that both this and the original sound a bit... awkward to my ear. I wouldn't say "X degrees warm", for example.}

Place the pot someplace warm (20 – 22 degrees).

Solution 4:

Place the pot at a(ny) location where it is 20–22 degrees Celsius.

Or, to go to an extreme and sound really formal:

Ensure that the device used for containing items is located at a site which has a temperature between 20 degrees and 22 degrees Celsius, and should it fail to be at such a location, proceed to correct it until it is at a location at the desired temperature.

Solution 5:

As reported in the other answers, somewhere and where are superfluous; it's enough to say where.

Place the pot where the temperature is 20-22 degrees.
Place the pot where the cat cannot reach it.